diff --git a/backend/Dockerfile b/backend/Dockerfile
index f09a89eb..bb3464c3 100644
--- a/backend/Dockerfile
+++ b/backend/Dockerfile
@@ -44,7 +44,6 @@ RUN npm install --silent --only=production
 
 COPY ./docs ./docs
 COPY ./backend/i18n ./backend/i18n
-COPY ./backend/.env ./backend/.env
 
 EXPOSE 3000
 
diff --git a/backend/package.json b/backend/package.json
index 83db321f..3a89eb87 100644
--- a/backend/package.json
+++ b/backend/package.json
@@ -7,7 +7,7 @@
     "main": "dist/app.js",
     "scripts": {
         "build": "cross-env NODE_ENV=production tsc --build",
-        "dev": "cross-env NODE_ENV=development tsx watch --env-file=.env.development.local src/app.ts",
+        "dev": "cross-env NODE_ENV=development tsx tool/seed.ts; tsx watch --env-file=.env.development.local src/app.ts",
         "start": "cross-env NODE_ENV=production node --env-file=.env dist/app.js",
         "format": "prettier --write src/",
         "format-check": "prettier --check src/",
diff --git a/backend/src/config.ts b/backend/src/config.ts
index 9b4702b5..9b209ada 100644
--- a/backend/src/config.ts
+++ b/backend/src/config.ts
@@ -5,3 +5,4 @@ export const DWENGO_API_BASE = getEnvVar(envVars.LearningContentRepoApiBaseUrl);
 export const FALLBACK_LANG = getEnvVar(envVars.FallbackLanguage);
 
 export const FALLBACK_SEQ_NUM = 1;
+export const FALLBACK_VERSION_NUM = 1;
diff --git a/backend/src/controllers/answers.ts b/backend/src/controllers/answers.ts
new file mode 100644
index 00000000..38cebe84
--- /dev/null
+++ b/backend/src/controllers/answers.ts
@@ -0,0 +1,99 @@
+import { Request, Response } from 'express';
+import { requireFields } from './error-helper.js';
+import { getLearningObjectId, getQuestionId } from './questions.js';
+import { createAnswer, deleteAnswer, getAnswer, getAnswersByQuestion, updateAnswer } from '../services/answers.js';
+import { FALLBACK_SEQ_NUM } from '../config.js';
+import { AnswerData } from '@dwengo-1/common/interfaces/answer';
+
+export async function getAllAnswersHandler(req: Request, res: Response): Promise<void> {
+    const hruid = req.params.hruid;
+    const version = req.params.version;
+    const language = req.query.lang as string;
+    const seq = req.params.seq;
+    const full = req.query.full === 'true';
+    requireFields({ hruid });
+
+    const learningObjectId = getLearningObjectId(hruid, version, language);
+    const questionId = getQuestionId(learningObjectId, seq);
+
+    const answers = await getAnswersByQuestion(questionId, full);
+
+    res.json({ answers });
+}
+
+export async function getAnswerHandler(req: Request, res: Response): Promise<void> {
+    const hruid = req.params.hruid;
+    const version = req.params.version;
+    const language = req.query.lang as string;
+    const seq = req.params.seq;
+    const seqAnswer = req.params.seqAnswer;
+    requireFields({ hruid });
+
+    const learningObjectId = getLearningObjectId(hruid, version, language);
+    const questionId = getQuestionId(learningObjectId, seq);
+
+    const sequenceNumber = Number(seqAnswer) || FALLBACK_SEQ_NUM;
+    const answer = await getAnswer(questionId, sequenceNumber);
+
+    res.json({ answer });
+}
+
+export async function createAnswerHandler(req: Request, res: Response): Promise<void> {
+    const hruid = req.params.hruid;
+    const version = req.params.version;
+    const language = req.query.lang as string;
+    const seq = req.params.seq;
+    requireFields({ hruid });
+
+    const learningObjectId = getLearningObjectId(hruid, version, language);
+    const questionId = getQuestionId(learningObjectId, seq);
+
+    const author = req.body.author as string;
+    const content = req.body.content as string;
+    requireFields({ author, content });
+
+    const answerData = req.body as AnswerData;
+
+    const answer = await createAnswer(questionId, answerData);
+
+    res.json({ answer });
+}
+
+export async function deleteAnswerHandler(req: Request, res: Response): Promise<void> {
+    const hruid = req.params.hruid;
+    const version = req.params.version;
+    const language = req.query.lang as string;
+    const seq = req.params.seq;
+    const seqAnswer = req.params.seqAnswer;
+    requireFields({ hruid });
+
+    const learningObjectId = getLearningObjectId(hruid, version, language);
+    const questionId = getQuestionId(learningObjectId, seq);
+
+    const sequenceNumber = Number(seqAnswer) || FALLBACK_SEQ_NUM;
+    const answer = await deleteAnswer(questionId, sequenceNumber);
+
+    res.json({ answer });
+}
+
+export async function updateAnswerHandler(req: Request, res: Response): Promise<void> {
+    const hruid = req.params.hruid;
+    const version = req.params.version;
+    const language = req.query.lang as string;
+    const seq = req.params.seq;
+    const seqAnswer = req.params.seqAnswer;
+    requireFields({ hruid });
+
+    const learningObjectId = getLearningObjectId(hruid, version, language);
+    const questionId = getQuestionId(learningObjectId, seq);
+
+    const content = req.body.content as string;
+    requireFields({ content });
+
+    const answerData = req.body as AnswerData;
+
+    const sequenceNumber = Number(seqAnswer) || FALLBACK_SEQ_NUM;
+    const answer = await updateAnswer(questionId, sequenceNumber, answerData);
+
+    res.json({ answer });
+}
diff --git a/backend/src/controllers/assignments.ts b/backend/src/controllers/assignments.ts
index 1520fc10..2ecb35cb 100644
--- a/backend/src/controllers/assignments.ts
+++ b/backend/src/controllers/assignments.ts
@@ -1,77 +1,94 @@
 import { Request, Response } from 'express';
-import { createAssignment, getAllAssignments, getAssignment, getAssignmentsSubmissions } from '../services/assignments.js';
+import {
+    createAssignment,
+    deleteAssignment,
+    getAllAssignments,
+    getAssignment,
+    getAssignmentsSubmissions,
+    putAssignment,
+} from '../services/assignments.js';
 import { AssignmentDTO } from '@dwengo-1/common/interfaces/assignment';
+import { requireFields } from './error-helper.js';
+import { BadRequestException } from '../exceptions/bad-request-exception.js';
+import { Assignment } from '../entities/assignments/assignment.entity.js';
+import { EntityDTO } from '@mikro-orm/core';
 
-// Typescript is annoying with parameter forwarding from class.ts
-interface AssignmentParams {
-    classid: string;
-    id: string;
-}
-
-export async function getAllAssignmentsHandler(req: Request<AssignmentParams>, res: Response): Promise<void> {
-    const classid = req.params.classid;
+export async function getAllAssignmentsHandler(req: Request, res: Response): Promise<void> {
+    const classId = req.params.classid;
     const full = req.query.full === 'true';
 
-    const assignments = await getAllAssignments(classid, full);
+    const assignments = await getAllAssignments(classId, full);
 
-    res.json({
-        assignments: assignments,
-    });
+    res.json({ assignments });
 }
 
-export async function createAssignmentHandler(req: Request<AssignmentParams>, res: Response): Promise<void> {
+export async function createAssignmentHandler(req: Request, res: Response): Promise<void> {
     const classid = req.params.classid;
+    const description = req.body.description;
+    const language = req.body.language;
+    const learningPath = req.body.learningPath;
+    const title = req.body.title;
+
+    requireFields({ description, language, learningPath, title });
+
     const assignmentData = req.body as AssignmentDTO;
-
-    if (!assignmentData.description || !assignmentData.language || !assignmentData.learningPath || !assignmentData.title) {
-        res.status(400).json({
-            error: 'Missing one or more required fields: title, description, learningPath, language',
-        });
-        return;
-    }
-
     const assignment = await createAssignment(classid, assignmentData);
 
-    if (!assignment) {
-        res.status(500).json({ error: 'Could not create assignment ' });
-        return;
-    }
-
-    res.status(201).json(assignment);
+    res.json({ assignment });
 }
 
-export async function getAssignmentHandler(req: Request<AssignmentParams>, res: Response): Promise<void> {
+export async function getAssignmentHandler(req: Request, res: Response): Promise<void> {
     const id = Number(req.params.id);
     const classid = req.params.classid;
+    requireFields({ id, classid });
 
     if (isNaN(id)) {
-        res.status(400).json({ error: 'Assignment id must be a number' });
-        return;
+        throw new BadRequestException('Assignment id should be a number');
     }
 
     const assignment = await getAssignment(classid, id);
 
-    if (!assignment) {
-        res.status(404).json({ error: 'Assignment not found' });
-        return;
-    }
-
-    res.json(assignment);
+    res.json({ assignment });
 }
 
-export async function getAssignmentsSubmissionsHandler(req: Request<AssignmentParams>, res: Response): Promise<void> {
+export async function putAssignmentHandler(req: Request, res: Response): Promise<void> {
+    const id = Number(req.params.id);
+    const classid = req.params.classid;
+    requireFields({ id, classid });
+
+    if (isNaN(id)) {
+        throw new BadRequestException('Assignment id should be a number');
+    }
+
+    const assignmentData = req.body as Partial<EntityDTO<Assignment>>;
+    const assignment = await putAssignment(classid, id, assignmentData);
+
+    res.json({ assignment });
+}
+
+export async function deleteAssignmentHandler(req: Request, _res: Response): Promise<void> {
+    const id = Number(req.params.id);
+    const classid = req.params.classid;
+    requireFields({ id, classid });
+
+    if (isNaN(id)) {
+        throw new BadRequestException('Assignment id should be a number');
+    }
+
+    await deleteAssignment(classid, id);
+}
+
+export async function getAssignmentsSubmissionsHandler(req: Request, res: Response): Promise<void> {
     const classid = req.params.classid;
     const assignmentNumber = Number(req.params.id);
     const full = req.query.full === 'true';
+    requireFields({ assignmentNumber, classid });
 
     if (isNaN(assignmentNumber)) {
-        res.status(400).json({ error: 'Assignment id must be a number' });
-        return;
+        throw new BadRequestException('Assignment id should be a number');
     }
 
     const submissions = await getAssignmentsSubmissions(classid, assignmentNumber, full);
 
-    res.json({
-        submissions: submissions,
-    });
+    res.json({ submissions });
 }
diff --git a/backend/src/controllers/classes.ts b/backend/src/controllers/classes.ts
index a041bf22..6f253547 100644
--- a/backend/src/controllers/classes.ts
+++ b/backend/src/controllers/classes.ts
@@ -1,66 +1,132 @@
 import { Request, Response } from 'express';
-import { createClass, getAllClasses, getClass, getClassStudents, getClassStudentsIds, getClassTeacherInvitations } from '../services/classes.js';
+import {
+    addClassStudent,
+    addClassTeacher,
+    createClass,
+    deleteClass,
+    deleteClassStudent,
+    deleteClassTeacher,
+    getAllClasses,
+    getClass,
+    getClassStudents,
+    getClassTeacherInvitations,
+    getClassTeachers,
+    putClass,
+} from '../services/classes.js';
 import { ClassDTO } from '@dwengo-1/common/interfaces/class';
+import { requireFields } from './error-helper.js';
+import { EntityDTO } from '@mikro-orm/core';
+import { Class } from '../entities/classes/class.entity.js';
 
 export async function getAllClassesHandler(req: Request, res: Response): Promise<void> {
     const full = req.query.full === 'true';
     const classes = await getAllClasses(full);
 
-    res.json({
-        classes: classes,
-    });
+    res.json({ classes });
 }
 
 export async function createClassHandler(req: Request, res: Response): Promise<void> {
+    const displayName = req.body.displayName;
+    requireFields({ displayName });
+
     const classData = req.body as ClassDTO;
-
-    if (!classData.displayName) {
-        res.status(400).json({
-            error: 'Missing one or more required fields: displayName',
-        });
-        return;
-    }
-
     const cls = await createClass(classData);
 
-    if (!cls) {
-        res.status(500).json({ error: 'Something went wrong while creating class' });
-        return;
-    }
-
-    res.status(201).json(cls);
+    res.json({ class: cls });
 }
 
 export async function getClassHandler(req: Request, res: Response): Promise<void> {
     const classId = req.params.id;
+    requireFields({ classId });
+
     const cls = await getClass(classId);
 
-    if (!cls) {
-        res.status(404).json({ error: 'Class not found' });
-        return;
-    }
+    res.json({ class: cls });
+}
 
-    res.json(cls);
+export async function putClassHandler(req: Request, res: Response): Promise<void> {
+    const classId = req.params.id;
+    requireFields({ classId });
+
+    const newData = req.body as Partial<EntityDTO<Class>>;
+    const cls = await putClass(classId, newData);
+
+    res.json({ class: cls });
+}
+
+export async function deleteClassHandler(req: Request, res: Response): Promise<void> {
+    const classId = req.params.id;
+    const cls = await deleteClass(classId);
+
+    res.json({ class: cls });
 }
 
 export async function getClassStudentsHandler(req: Request, res: Response): Promise<void> {
     const classId = req.params.id;
     const full = req.query.full === 'true';
+    requireFields({ classId });
 
-    const students = full ? await getClassStudents(classId) : await getClassStudentsIds(classId);
+    const students = await getClassStudents(classId, full);
 
-    res.json({
-        students: students,
-    });
+    res.json({ students });
+}
+
+export async function getClassTeachersHandler(req: Request, res: Response): Promise<void> {
+    const classId = req.params.id;
+    const full = req.query.full === 'true';
+    requireFields({ classId });
+
+    const teachers = await getClassTeachers(classId, full);
+
+    res.json({ teachers });
 }
 
 export async function getTeacherInvitationsHandler(req: Request, res: Response): Promise<void> {
     const classId = req.params.id;
     const full = req.query.full === 'true';
+    requireFields({ classId });
 
     const invitations = await getClassTeacherInvitations(classId, full);
 
-    res.json({
-        invitations: invitations,
-    });
+    res.json({ invitations });
+}
+
+export async function deleteClassStudentHandler(req: Request, res: Response): Promise<void> {
+    const classId = req.params.id;
+    const username = req.params.username;
+    requireFields({ classId, username });
+
+    const cls = await deleteClassStudent(classId, username);
+
+    res.json({ class: cls });
+}
+
+export async function deleteClassTeacherHandler(req: Request, res: Response): Promise<void> {
+    const classId = req.params.id;
+    const username = req.params.username;
+    requireFields({ classId, username });
+
+    const cls = await deleteClassTeacher(classId, username);
+
+    res.json({ class: cls });
+}
+
+export async function addClassStudentHandler(req: Request, res: Response): Promise<void> {
+    const classId = req.params.id;
+    const username = req.body.username;
+    requireFields({ classId, username });
+
+    const cls = await addClassStudent(classId, username);
+
+    res.json({ class: cls });
+}
+
+export async function addClassTeacherHandler(req: Request, res: Response): Promise<void> {
+    const classId = req.params.id;
+    const username = req.body.username;
+    requireFields({ classId, username });
+
+    const cls = await addClassTeacher(classId, username);
+
+    res.json({ class: cls });
 }
diff --git a/backend/src/controllers/groups.ts b/backend/src/controllers/groups.ts
index 989066a6..ec177dcc 100644
--- a/backend/src/controllers/groups.ts
+++ b/backend/src/controllers/groups.ts
@@ -1,100 +1,104 @@
 import { Request, Response } from 'express';
-import { createGroup, getAllGroups, getGroup, getGroupSubmissions } from '../services/groups.js';
+import { createGroup, deleteGroup, getAllGroups, getGroup, getGroupSubmissions, putGroup } from '../services/groups.js';
 import { GroupDTO } from '@dwengo-1/common/interfaces/group';
+import { requireFields } from './error-helper.js';
+import { BadRequestException } from '../exceptions/bad-request-exception.js';
+import { EntityDTO } from '@mikro-orm/core';
+import { Group } from '../entities/assignments/group.entity.js';
 
-// Typescript is annoywith with parameter forwarding from class.ts
-interface GroupParams {
-    classid: string;
-    assignmentid: string;
-    groupid?: string;
-}
-
-export async function getGroupHandler(req: Request<GroupParams>, res: Response): Promise<void> {
-    const classId = req.params.classid;
-    const full = req.query.full === 'true';
-    const assignmentId = Number(req.params.assignmentid);
+function checkGroupFields(classId: string, assignmentId: number, groupId: number): void {
+    requireFields({ classId, assignmentId, groupId });
 
     if (isNaN(assignmentId)) {
-        res.status(400).json({ error: 'Assignment id must be a number' });
-        return;
+        throw new BadRequestException('Assignment id must be a number');
     }
 
-    const groupId = Number(req.params.groupid!); // Can't be undefined
-
     if (isNaN(groupId)) {
-        res.status(400).json({ error: 'Group id must be a number' });
-        return;
+        throw new BadRequestException('Group id must be a number');
     }
+}
 
-    const group = await getGroup(classId, assignmentId, groupId, full);
+export async function getGroupHandler(req: Request, res: Response): Promise<void> {
+    const classId = req.params.classid;
+    const assignmentId = parseInt(req.params.assignmentid);
+    const groupId = parseInt(req.params.groupid);
+    checkGroupFields(classId, assignmentId, groupId);
 
-    if (!group) {
-        res.status(404).json({ error: 'Group not found' });
-        return;
-    }
+    const group = await getGroup(classId, assignmentId, groupId);
 
-    res.json(group);
+    res.json({ group });
+}
+
+export async function putGroupHandler(req: Request, res: Response): Promise<void> {
+    const classId = req.params.classid;
+    const assignmentId = parseInt(req.params.assignmentid);
+    const groupId = parseInt(req.params.groupid);
+    checkGroupFields(classId, assignmentId, groupId);
+
+    const group = await putGroup(classId, assignmentId, groupId, req.body as Partial<EntityDTO<Group>>);
+
+    res.json({ group });
+}
+
+export async function deleteGroupHandler(req: Request, res: Response): Promise<void> {
+    const classId = req.params.classid;
+    const assignmentId = parseInt(req.params.assignmentid);
+    const groupId = parseInt(req.params.groupid);
+    checkGroupFields(classId, assignmentId, groupId);
+
+    const group = await deleteGroup(classId, assignmentId, groupId);
+
+    res.json({ group });
 }
 
 export async function getAllGroupsHandler(req: Request, res: Response): Promise<void> {
     const classId = req.params.classid;
-    const full = req.query.full === 'true';
-
     const assignmentId = Number(req.params.assignmentid);
+    const full = req.query.full === 'true';
+    requireFields({ classId, assignmentId });
 
     if (isNaN(assignmentId)) {
-        res.status(400).json({ error: 'Assignment id must be a number' });
-        return;
+        throw new BadRequestException('Assignment id must be a number');
     }
 
     const groups = await getAllGroups(classId, assignmentId, full);
 
-    res.json({
-        groups: groups,
-    });
+    res.json({ groups });
 }
 
 export async function createGroupHandler(req: Request, res: Response): Promise<void> {
     const classid = req.params.classid;
     const assignmentId = Number(req.params.assignmentid);
 
+    requireFields({ classid, assignmentId });
+
     if (isNaN(assignmentId)) {
-        res.status(400).json({ error: 'Assignment id must be a number' });
-        return;
+        throw new BadRequestException('Assignment id must be a number');
     }
 
     const groupData = req.body as GroupDTO;
     const group = await createGroup(groupData, classid, assignmentId);
 
-    if (!group) {
-        res.status(500).json({ error: 'Something went wrong while creating group' });
-        return;
-    }
-
-    res.status(201).json(group);
+    res.status(201).json({ group });
 }
 
 export async function getGroupSubmissionsHandler(req: Request, res: Response): Promise<void> {
     const classId = req.params.classid;
+    const assignmentId = Number(req.params.assignmentid);
+    const groupId = Number(req.params.groupid);
     const full = req.query.full === 'true';
 
-    const assignmentId = Number(req.params.assignmentid);
+    requireFields({ classId, assignmentId, groupId });
 
     if (isNaN(assignmentId)) {
-        res.status(400).json({ error: 'Assignment id must be a number' });
-        return;
+        throw new BadRequestException('Assignment id must be a number');
     }
 
-    const groupId = Number(req.params.groupid); // Can't be undefined
-
     if (isNaN(groupId)) {
-        res.status(400).json({ error: 'Group id must be a number' });
-        return;
+        throw new BadRequestException('Group id must be a number');
     }
 
     const submissions = await getGroupSubmissions(classId, assignmentId, groupId, full);
 
-    res.json({
-        submissions: submissions,
-    });
+    res.json({ submissions });
 }
diff --git a/backend/src/controllers/learning-objects.ts b/backend/src/controllers/learning-objects.ts
index a2510631..83aa33f9 100644
--- a/backend/src/controllers/learning-objects.ts
+++ b/backend/src/controllers/learning-objects.ts
@@ -6,9 +6,9 @@ import attachmentService from '../services/learning-objects/attachment-service.j
 import { BadRequestException } from '../exceptions/bad-request-exception.js';
 import { NotFoundException } from '../exceptions/not-found-exception.js';
 import { envVars, getEnvVar } from '../util/envVars.js';
-import { FilteredLearningObject, LearningObjectIdentifier, LearningPathIdentifier } from '@dwengo-1/common/interfaces/learning-content';
+import { FilteredLearningObject, LearningObjectIdentifierDTO, LearningPathIdentifier } from '@dwengo-1/common/interfaces/learning-content';
 
-function getLearningObjectIdentifierFromRequest(req: Request): LearningObjectIdentifier {
+function getLearningObjectIdentifierFromRequest(req: Request): LearningObjectIdentifierDTO {
     if (!req.params.hruid) {
         throw new BadRequestException('HRUID is required.');
     }
diff --git a/backend/src/controllers/questions.ts b/backend/src/controllers/questions.ts
index 4df165ee..3fdfdacd 100644
--- a/backend/src/controllers/questions.ts
+++ b/backend/src/controllers/questions.ts
@@ -3,175 +3,122 @@ import {
     createQuestion,
     deleteQuestion,
     getAllQuestions,
-    getAnswersByQuestion,
     getQuestion,
     getQuestionsAboutLearningObjectInAssignment,
+    updateQuestion
 } from '../services/questions.js';
-import { FALLBACK_LANG, FALLBACK_SEQ_NUM } from '../config.js';
+import { FALLBACK_LANG, FALLBACK_SEQ_NUM, FALLBACK_VERSION_NUM } from '../config.js';
 import { LearningObjectIdentifier } from '../entities/content/learning-object-identifier.js';
-import { QuestionDTO, QuestionId } from '@dwengo-1/common/interfaces/question';
+import {QuestionData, QuestionDTO, QuestionId} from '@dwengo-1/common/interfaces/question';
 import { Language } from '@dwengo-1/common/util/language';
-import { AnswerDTO, AnswerId } from '@dwengo-1/common/interfaces/answer';
-
-interface QuestionPathParams {
-    hruid: string;
-    version: string;
-}
-
-interface QuestionQueryParams {
-    lang: string;
-}
-
-function getObjectId<ResBody, ReqBody>(
-    req: Request<QuestionPathParams, ResBody, ReqBody, QuestionQueryParams>,
-    res: Response
-): LearningObjectIdentifier | null {
-    const { hruid, version } = req.params;
-    const lang = req.query.lang;
-
-    if (!hruid || !version) {
-        res.status(400).json({ error: 'Missing required parameters.' });
-        return null;
-    }
+import { requireFields } from './error-helper.js';
 
+export function getLearningObjectId(hruid: string, version: string, lang: string): LearningObjectIdentifier {
     return {
         hruid,
-        language: (lang as Language) || FALLBACK_LANG,
-        version: Number(version),
+        language: (lang || FALLBACK_LANG) as Language,
+        version: Number(version) || FALLBACK_VERSION_NUM,
     };
 }
 
-interface GetQuestionIdPathParams extends QuestionPathParams {
-    seq: string;
-}
-function getQuestionId<ReqBody, ResBody>(
-    req: Request<GetQuestionIdPathParams, ReqBody, ResBody, QuestionQueryParams>,
-    res: Response
-): QuestionId | null {
-    const seq = req.params.seq;
-    const learningObjectIdentifier = getObjectId(req, res);
-
-    if (!learningObjectIdentifier) {
-        return null;
-    }
-
+export function getQuestionId(learningObjectIdentifier: LearningObjectIdentifier, seq: string): QuestionId {
     return {
         learningObjectIdentifier,
         sequenceNumber: seq ? Number(seq) : FALLBACK_SEQ_NUM,
     };
 }
 
-interface GetAllQuestionsQueryParams extends QuestionQueryParams {
-    classId?: string;
-    assignmentId?: number;
-    forStudent?: string;
-    full?: boolean;
-}
+export async function getAllQuestionsHandler(req: Request, res: Response): Promise<void> {
+    const hruid = req.params.hruid;
+    const version = req.params.version;
+    const language = req.query.lang as string;
+    const full = req.query.full === 'true';
+    requireFields({ hruid });
 
-export async function getAllQuestionsHandler(
-    req: Request<QuestionPathParams, QuestionDTO[] | QuestionId[], unknown, GetAllQuestionsQueryParams>,
-    res: Response
-): Promise<void> {
-    const objectId = getObjectId(req, res);
-    const full = req.query.full;
+    const learningObjectId = getLearningObjectId(hruid, version, language);
 
-    if (!objectId) {
-        return;
-    }
     let questions: QuestionDTO[] | QuestionId[];
     if (req.query.classId && req.query.assignmentId) {
         questions = await getQuestionsAboutLearningObjectInAssignment(
-            objectId,
-            req.query.classId,
-            req.query.assignmentId,
+            learningObjectId,
+            req.query.classId as string,
+            parseInt(req.query.assignmentId as string),
             full ?? false,
-            req.query.forStudent
+            req.query.forStudent as string | undefined
         );
     } else {
-        questions = await getAllQuestions(objectId, full ?? false);
+        questions = await getAllQuestions(learningObjectId, full ?? false);
     }
 
-    if (!questions) {
-        res.status(404).json({ error: `Questions not found.` });
-    } else {
-        res.json({ questions: questions });
-    }
+    res.json({ questions });
 }
 
-export async function getQuestionHandler(
-    req: Request<GetQuestionIdPathParams, QuestionDTO[] | QuestionId[], unknown, QuestionQueryParams>,
-    res: Response
-): Promise<void> {
-    const questionId = getQuestionId(req, res);
+export async function getQuestionHandler(req: Request, res: Response): Promise<void> {
+    const hruid = req.params.hruid;
+    const version = req.params.version;
+    const language = req.query.lang as string;
+    const seq = req.params.seq;
+    requireFields({ hruid });
 
-    if (!questionId) {
-        return;
-    }
+    const learningObjectId = getLearningObjectId(hruid, version, language);
+    const questionId = getQuestionId(learningObjectId, seq);
 
     const question = await getQuestion(questionId);
 
-    if (!question) {
-        res.status(404).json({ error: `Question not found.` });
-    } else {
-        res.json(question);
-    }
-}
-
-interface GetQuestionAnswersQueryParams extends QuestionQueryParams {
-    full: boolean;
-}
-export async function getQuestionAnswersHandler(
-    req: Request<GetQuestionIdPathParams, { answers: AnswerDTO[] | AnswerId[] }, unknown, GetQuestionAnswersQueryParams>,
-    res: Response
-): Promise<void> {
-    const questionId = getQuestionId(req, res);
-    const full = req.query.full;
-
-    if (!questionId) {
-        return;
-    }
-
-    const answers = await getAnswersByQuestion(questionId, full);
-
-    if (!answers) {
-        res.status(404).json({ error: `Questions not found` });
-    } else {
-        res.json({ answers: answers });
-    }
+    res.json({ question });
 }
 
 export async function createQuestionHandler(req: Request, res: Response): Promise<void> {
-    const questionDTO = req.body as QuestionDTO;
+    const hruid = req.params.hruid;
+    const version = req.params.version;
+    const language = req.query.lang as string;
+    requireFields({ hruid });
 
-    if (!questionDTO.learningObjectIdentifier || !questionDTO.author || !questionDTO.inGroup || !questionDTO.content) {
-        res.status(400).json({ error: 'Missing required fields: identifier, author, inGroup, and content' });
-        return;
-    }
+    const loId = getLearningObjectId(hruid, version, language);
 
-    const question = await createQuestion(questionDTO);
+    const author = req.body.author as string;
+    const content = req.body.content as string;
+    const inGroup = req.body.inGroup;
+    requireFields({ author, content, inGroup });
 
-    if (!question) {
-        res.status(400).json({ error: 'Could not create question' });
-    } else {
-        res.json(question);
-    }
+    const questionData = req.body as QuestionData;
+
+    const question = await createQuestion(loId, questionData);
+
+    res.json({ question });
 }
 
-export async function deleteQuestionHandler(
-    req: Request<GetQuestionIdPathParams, QuestionDTO, unknown, QuestionQueryParams>,
-    res: Response
-): Promise<void> {
-    const questionId = getQuestionId(req, res);
+export async function deleteQuestionHandler(req: Request, res: Response): Promise<void> {
+    const hruid = req.params.hruid;
+    const version = req.params.version;
+    const language = req.query.lang as string;
+    const seq = req.params.seq;
+    requireFields({ hruid });
 
-    if (!questionId) {
-        return;
-    }
+    const learningObjectId = getLearningObjectId(hruid, version, language);
+    const questionId = getQuestionId(learningObjectId, seq);
 
     const question = await deleteQuestion(questionId);
 
-    if (!question) {
-        res.status(400).json({ error: 'Could not find nor delete question' });
-    } else {
-        res.json(question);
-    }
+    res.json({ question });
+}
+
+export async function updateQuestionHandler(req: Request, res: Response): Promise<void> {
+    const hruid = req.params.hruid;
+    const version = req.params.version;
+    const language = req.query.lang as string;
+    const seq = req.params.seq;
+    requireFields({ hruid });
+
+    const learningObjectId = getLearningObjectId(hruid, version, language);
+    const questionId = getQuestionId(learningObjectId, seq);
+
+    const content = req.body.content as string;
+    requireFields({ content });
+
+    const questionData = req.body as QuestionData;
+
+    const question = await updateQuestion(questionId, questionData);
+
+    res.json({ question });
 }
diff --git a/backend/src/controllers/submissions.ts b/backend/src/controllers/submissions.ts
index 73f1317f..4714c1c4 100644
--- a/backend/src/controllers/submissions.ts
+++ b/backend/src/controllers/submissions.ts
@@ -1,28 +1,20 @@
 import { Request, Response } from 'express';
-import { createSubmission, deleteSubmission, getSubmission, getSubmissionsForLearningObjectAndAssignment } from '../services/submissions.js';
+import {
+    createSubmission,
+    deleteSubmission,
+    getAllSubmissions,
+    getSubmission,
+    getSubmissionsForLearningObjectAndAssignment
+} from '../services/submissions.js';
 import { SubmissionDTO } from '@dwengo-1/common/interfaces/submission';
 import { Language, languageMap } from '@dwengo-1/common/util/language';
-import { Submission } from '../entities/assignments/submission.entity';
+import { BadRequestException } from '../exceptions/bad-request-exception.js';
+import { requireFields } from './error-helper.js';
+import { LearningObjectIdentifier } from '../entities/content/learning-object-identifier.js';
 
-interface SubmissionParams {
-    hruid: string;
-    id: number;
-}
-
-interface SubmissionQuery {
-    language: string;
-    version: number;
-}
-
-interface SubmissionsQuery extends SubmissionQuery {
-    classId: string;
-    assignmentId: number;
-    studentUsername?: string;
-}
-
-export async function getSubmissionsHandler(req: Request<SubmissionParams, Submission[], null, SubmissionsQuery>, res: Response): Promise<void> {
+export async function getSubmissionsHandler(req: Request, res: Response): Promise<void> {
     const loHruid = req.params.hruid;
-    const lang = languageMap[req.query.language] || Language.Dutch;
+    const lang = languageMap[req.query.language as string] || Language.Dutch;
     const version = req.query.version || 1;
 
     const submissions = await getSubmissionsForLearningObjectAndAssignment(loHruid, lang, version, req.query.classId, req.query.assignmentId);
@@ -30,54 +22,57 @@ export async function getSubmissionsHandler(req: Request<SubmissionParams, Submi
     res.json(submissions);
 }
 
-export async function getSubmissionHandler(req: Request<SubmissionParams>, res: Response): Promise<void> {
+
+export async function getSubmissionHandler(req: Request, res: Response): Promise<void> {
     const lohruid = req.params.hruid;
-    const submissionNumber = Number(req.params.id);
-
-    if (isNaN(submissionNumber)) {
-        res.status(400).json({ error: 'Submission number is not a number' });
-        return;
-    }
-
     const lang = languageMap[req.query.language as string] || Language.Dutch;
     const version = (req.query.version || 1) as number;
+    const submissionNumber = Number(req.params.id);
+    requireFields({ lohruid, submissionNumber });
 
-    const submission = await getSubmission(lohruid, lang, version, submissionNumber);
-
-    if (!submission) {
-        res.status(404).json({ error: 'Submission not found' });
-        return;
+    if (isNaN(submissionNumber)) {
+        throw new BadRequestException('Submission number must be a number');
     }
 
-    res.json(submission);
+    const loId = new LearningObjectIdentifier(lohruid, lang, version);
+    const submission = await getSubmission(loId, submissionNumber);
+
+    res.json({ submission });
 }
 
+export async function getAllSubmissionsHandler(req: Request, res: Response): Promise<void> {
+    const lohruid = req.params.hruid;
+    const lang = languageMap[req.query.language as string] || Language.Dutch;
+    const version = (req.query.version || 1) as number;
+    requireFields({ lohruid });
+
+    const loId = new LearningObjectIdentifier(lohruid, lang, version);
+    const submissions = await getAllSubmissions(loId);
+
+    res.json({ submissions });
+}
+
+// TODO: gerald moet nog dingen toevoegen aan de databank voor dat dit gefinaliseerd kan worden
 export async function createSubmissionHandler(req: Request, res: Response): Promise<void> {
     const submissionDTO = req.body as SubmissionDTO;
-
     const submission = await createSubmission(submissionDTO);
 
-    if (!submission) {
-        res.status(400).json({ error: 'Failed to create submission' });
-        return;
-    }
-
-    res.json(submission);
+    res.json({ submission });
 }
 
 export async function deleteSubmissionHandler(req: Request, res: Response): Promise<void> {
     const hruid = req.params.hruid;
-    const submissionNumber = Number(req.params.id);
-
     const lang = languageMap[req.query.language as string] || Language.Dutch;
     const version = (req.query.version || 1) as number;
+    const submissionNumber = Number(req.params.id);
+    requireFields({ hruid, submissionNumber });
 
-    const submission = await deleteSubmission(hruid, lang, version, submissionNumber);
-
-    if (!submission) {
-        res.status(404).json({ error: 'Submission not found' });
-        return;
+    if (isNaN(submissionNumber)) {
+        throw new BadRequestException('Submission number must be a number');
     }
 
-    res.json(submission);
+    const loId = new LearningObjectIdentifier(hruid, lang, version);
+    const submission = await deleteSubmission(loId, submissionNumber);
+
+    res.json({ submission });
 }
diff --git a/backend/src/controllers/teachers.ts b/backend/src/controllers/teachers.ts
index 9275ca92..c8063f80 100644
--- a/backend/src/controllers/teachers.ts
+++ b/backend/src/controllers/teachers.ts
@@ -81,16 +81,15 @@ export async function getTeacherQuestionHandler(req: Request, res: Response): Pr
 }
 
 export async function getStudentJoinRequestHandler(req: Request, res: Response): Promise<void> {
-    const username = req.query.username as string;
     const classId = req.params.classId;
-    requireFields({ username, classId });
+    requireFields({ classId });
 
     const joinRequests = await getJoinRequestsByClass(classId);
     res.json({ joinRequests });
 }
 
 export async function updateStudentJoinRequestHandler(req: Request, res: Response): Promise<void> {
-    const studentUsername = req.query.studentUsername as string;
+    const studentUsername = req.params.studentUsername;
     const classId = req.params.classId;
     const accepted = req.body.accepted !== 'false'; // Default = true
     requireFields({ studentUsername, classId });
diff --git a/backend/src/data/assignments/submission-repository.ts b/backend/src/data/assignments/submission-repository.ts
index c82ed9c3..93089e3b 100644
--- a/backend/src/data/assignments/submission-repository.ts
+++ b/backend/src/data/assignments/submission-repository.ts
@@ -18,6 +18,14 @@ export class SubmissionRepository extends DwengoEntityRepository<Submission> {
         });
     }
 
+    public async findByLearningObject(loId: LearningObjectIdentifier): Promise<Submission[]> {
+        return this.find({
+            learningObjectHruid: loId.hruid,
+            learningObjectLanguage: loId.language,
+            learningObjectVersion: loId.version,
+        });
+    }
+
     public async findMostRecentSubmissionForStudent(loId: LearningObjectIdentifier, submitter: Student): Promise<Submission | null> {
         return this.findOne(
             {
diff --git a/backend/src/data/questions/answer-repository.ts b/backend/src/data/questions/answer-repository.ts
index a50bfd28..54f67a01 100644
--- a/backend/src/data/questions/answer-repository.ts
+++ b/backend/src/data/questions/answer-repository.ts
@@ -2,6 +2,7 @@ import { DwengoEntityRepository } from '../dwengo-entity-repository.js';
 import { Answer } from '../../entities/questions/answer.entity.js';
 import { Question } from '../../entities/questions/question.entity.js';
 import { Teacher } from '../../entities/users/teacher.entity.js';
+import { Loaded } from '@mikro-orm/core';
 
 export class AnswerRepository extends DwengoEntityRepository<Answer> {
     public async createAnswer(answer: { toQuestion: Question; author: Teacher; content: string }): Promise<Answer> {
@@ -19,10 +20,21 @@ export class AnswerRepository extends DwengoEntityRepository<Answer> {
             orderBy: { sequenceNumber: 'ASC' },
         });
     }
+    public async findAnswer(question: Question, sequenceNumber: number): Promise<Loaded<Answer> | null> {
+        return this.findOne({
+            toQuestion: question,
+            sequenceNumber,
+        });
+    }
     public async removeAnswerByQuestionAndSequenceNumber(question: Question, sequenceNumber: number): Promise<void> {
         return this.deleteWhere({
             toQuestion: question,
             sequenceNumber: sequenceNumber,
         });
     }
+    public async updateContent(answer: Answer, newContent: string): Promise<Answer> {
+        answer.content = newContent;
+        await this.save(answer);
+        return answer;
+    }
 }
diff --git a/backend/src/data/questions/question-repository.ts b/backend/src/data/questions/question-repository.ts
index 6b961e07..faaf3528 100644
--- a/backend/src/data/questions/question-repository.ts
+++ b/backend/src/data/questions/question-repository.ts
@@ -3,8 +3,9 @@ import { Question } from '../../entities/questions/question.entity.js';
 import { LearningObjectIdentifier } from '../../entities/content/learning-object-identifier.js';
 import { Student } from '../../entities/users/student.entity.js';
 import { LearningObject } from '../../entities/content/learning-object.entity.js';
+import { Assignment } from '../../entities/assignments/assignment.entity.js';
+import { Loaded } from '@mikro-orm/core';
 import { Group } from '../../entities/assignments/group.entity';
-import { Assignment } from '../../entities/assignments/assignment.entity';
 
 export class QuestionRepository extends DwengoEntityRepository<Question> {
     public async createQuestion(question: { loId: LearningObjectIdentifier; author: Student; inGroup: Group; content: string }): Promise<Question> {
@@ -59,6 +60,14 @@ export class QuestionRepository extends DwengoEntityRepository<Question> {
         });
     }
 
+    public async findAllByAssignment(assignment: Assignment): Promise<Question[]> {
+        return this.find({
+            author: assignment.groups.flatMap((group) => group.members),
+            learningObjectHruid: assignment.learningPathHruid,
+            learningObjectLanguage: assignment.learningPathLanguage,
+        });
+    }
+
     public async findAllByAuthor(author: Student): Promise<Question[]> {
         return this.findAll({
             where: { author },
@@ -97,4 +106,19 @@ export class QuestionRepository extends DwengoEntityRepository<Question> {
             },
         });
     }
+
+    public async findByLearningObjectAndSequenceNumber(loId: LearningObjectIdentifier, sequenceNumber: number): Promise<Loaded<Question> | null> {
+        return this.findOne({
+            learningObjectHruid: loId.hruid,
+            learningObjectLanguage: loId.language,
+            learningObjectVersion: loId.version,
+            sequenceNumber,
+        });
+    }
+
+    public async updateContent(question: Question, newContent: string): Promise<Question> {
+        question.content = newContent;
+        await this.save(question);
+        return question;
+    }
 }
diff --git a/backend/src/interfaces/answer.ts b/backend/src/interfaces/answer.ts
index 1f0d0625..513fc63e 100644
--- a/backend/src/interfaces/answer.ts
+++ b/backend/src/interfaces/answer.ts
@@ -1,14 +1,14 @@
-import { mapToUserDTO } from './user.js';
 import { mapToQuestionDTO, mapToQuestionDTOId } from './question.js';
 import { Answer } from '../entities/questions/answer.entity.js';
 import { AnswerDTO, AnswerId } from '@dwengo-1/common/interfaces/answer';
+import { mapToTeacherDTO } from './teacher.js';
 
 /**
  * Convert a Question entity to a DTO format.
  */
 export function mapToAnswerDTO(answer: Answer): AnswerDTO {
     return {
-        author: mapToUserDTO(answer.author),
+        author: mapToTeacherDTO(answer.author),
         toQuestion: mapToQuestionDTO(answer.toQuestion),
         sequenceNumber: answer.sequenceNumber!,
         timestamp: answer.timestamp.toISOString(),
diff --git a/backend/src/interfaces/assignment.ts b/backend/src/interfaces/assignment.ts
index d48a9083..7abb3d3c 100644
--- a/backend/src/interfaces/assignment.ts
+++ b/backend/src/interfaces/assignment.ts
@@ -8,19 +8,18 @@ import { AssignmentDTO } from '@dwengo-1/common/interfaces/assignment';
 export function mapToAssignmentDTOId(assignment: Assignment): AssignmentDTO {
     return {
         id: assignment.id!,
-        class: assignment.within.classId!,
+        within: assignment.within.classId!,
         title: assignment.title,
         description: assignment.description,
         learningPath: assignment.learningPathHruid,
         language: assignment.learningPathLanguage,
-        // Groups: assignment.groups.map(group => group.groupNumber),
     };
 }
 
 export function mapToAssignmentDTO(assignment: Assignment): AssignmentDTO {
     return {
         id: assignment.id!,
-        class: assignment.within.classId!,
+        within: assignment.within.classId!,
         title: assignment.title,
         description: assignment.description,
         learningPath: assignment.learningPathHruid,
diff --git a/backend/src/interfaces/class.ts b/backend/src/interfaces/class.ts
index 7b07fcf2..76fa5fd5 100644
--- a/backend/src/interfaces/class.ts
+++ b/backend/src/interfaces/class.ts
@@ -10,7 +10,6 @@ export function mapToClassDTO(cls: Class): ClassDTO {
         displayName: cls.displayName,
         teachers: cls.teachers.map((teacher) => teacher.username),
         students: cls.students.map((student) => student.username),
-        joinRequests: [], // TODO
     };
 }
 
diff --git a/backend/src/interfaces/group.ts b/backend/src/interfaces/group.ts
index abbd97de..924a4586 100644
--- a/backend/src/interfaces/group.ts
+++ b/backend/src/interfaces/group.ts
@@ -1,11 +1,14 @@
 import { Group } from '../entities/assignments/group.entity.js';
-import { mapToAssignment, mapToAssignmentDTO, mapToAssignmentDTOId } from './assignment.js';
-import { mapToStudent, mapToStudentDTO } from './student.js';
+import { mapToAssignment } from './assignment.js';
+import { mapToStudent } from './student.js';
+import { mapToAssignmentDTO } from './assignment.js';
+import { mapToStudentDTO } from './student.js';
 import { GroupDTO } from '@dwengo-1/common/interfaces/group';
 import { getGroupRepository } from '../data/repositories.js';
 import { AssignmentDTO } from '@dwengo-1/common/interfaces/assignment';
 import { Class } from '../entities/classes/class.entity.js';
 import { StudentDTO } from '@dwengo-1/common/interfaces/student';
+import {mapToClassDTO} from "./class";
 
 export function mapToGroup(groupDto: GroupDTO, clazz: Class): Group {
     const assignmentDto = groupDto.assignment as AssignmentDTO;
@@ -19,7 +22,8 @@ export function mapToGroup(groupDto: GroupDTO, clazz: Class): Group {
 
 export function mapToGroupDTO(group: Group): GroupDTO {
     return {
-        assignment: mapToAssignmentDTO(group.assignment), // ERROR: , group.assignment.within),
+        class: mapToClassDTO(group.assignment.within),
+        assignment: mapToAssignmentDTO(group.assignment),
         groupNumber: group.groupNumber!,
         members: group.members.map(mapToStudentDTO),
     };
@@ -27,7 +31,8 @@ export function mapToGroupDTO(group: Group): GroupDTO {
 
 export function mapToGroupDTOId(group: Group): GroupDTO {
     return {
-        assignment: mapToAssignmentDTOId(group.assignment),
+        class: group.assignment.within.classId!,
+        assignment: group.assignment.id!,
         groupNumber: group.groupNumber!,
     };
 }
@@ -37,6 +42,7 @@ export function mapToGroupDTOId(group: Group): GroupDTO {
  */
 export function mapToShallowGroupDTO(group: Group): GroupDTO {
     return {
+        class: group.assignment.within.classId!,
         assignment: group.assignment.id!,
         groupNumber: group.groupNumber!,
         members: group.members.map((member) => member.username),
diff --git a/backend/src/interfaces/question.ts b/backend/src/interfaces/question.ts
index 08887aba..50a61301 100644
--- a/backend/src/interfaces/question.ts
+++ b/backend/src/interfaces/question.ts
@@ -1,10 +1,11 @@
 import { Question } from '../entities/questions/question.entity.js';
 import { mapToStudentDTO } from './student.js';
 import { QuestionDTO, QuestionId } from '@dwengo-1/common/interfaces/question';
-import { LearningObjectIdentifier } from '@dwengo-1/common/interfaces/learning-content';
+import { LearningObjectIdentifierDTO } from '@dwengo-1/common/interfaces/learning-content';
+import { LearningObjectIdentifier } from '../entities/content/learning-object-identifier.js';
 import { mapToGroupDTOId } from './group.js';
 
-function getLearningObjectIdentifier(question: Question): LearningObjectIdentifier {
+function getLearningObjectIdentifier(question: Question): LearningObjectIdentifierDTO {
     return {
         hruid: question.learningObjectHruid,
         language: question.learningObjectLanguage,
@@ -12,6 +13,14 @@ function getLearningObjectIdentifier(question: Question): LearningObjectIdentifi
     };
 }
 
+export function mapToLearningObjectID(loID: LearningObjectIdentifierDTO): LearningObjectIdentifier {
+    return {
+        hruid: loID.hruid,
+        language: loID.language,
+        version: loID.version ?? 1,
+    };
+}
+
 /**
  * Convert a Question entity to a DTO format.
  */
diff --git a/backend/src/interfaces/submission.ts b/backend/src/interfaces/submission.ts
index bd80795a..085c795d 100644
--- a/backend/src/interfaces/submission.ts
+++ b/backend/src/interfaces/submission.ts
@@ -1,7 +1,10 @@
 import { Submission } from '../entities/assignments/submission.entity.js';
 import { mapToGroupDTO } from './group.js';
-import { mapToStudent, mapToStudentDTO } from './student.js';
+import { mapToStudentDTO } from './student.js';
 import { SubmissionDTO, SubmissionDTOId } from '@dwengo-1/common/interfaces/submission';
+import {getSubmissionRepository} from "../data/repositories";
+import {Student} from "../entities/users/student.entity";
+import {Group} from "../entities/assignments/group.entity";
 
 export function mapToSubmissionDTO(submission: Submission): SubmissionDTO {
     return {
@@ -29,16 +32,14 @@ export function mapToSubmissionDTOId(submission: Submission): SubmissionDTOId {
     };
 }
 
-export function mapToSubmission(submissionDTO: SubmissionDTO): Submission {
-    const submission = new Submission();
-    submission.learningObjectHruid = submissionDTO.learningObjectIdentifier.hruid;
-    submission.learningObjectLanguage = submissionDTO.learningObjectIdentifier.language;
-    submission.learningObjectVersion = submissionDTO.learningObjectIdentifier.version!;
-    // Submission.submissionNumber = submissionDTO.submissionNumber;
-    submission.submitter = mapToStudent(submissionDTO.submitter);
-    // Submission.submissionTime = submissionDTO.time;
-    // Submission.onBehalfOf =  submissionDTO.group!;
-    submission.content = submissionDTO.content;
-
-    return submission;
+export function mapToSubmission(submissionDTO: SubmissionDTO, submitter: Student, onBehalfOf: Group | undefined): Submission {
+    return getSubmissionRepository().create({
+        learningObjectHruid: submissionDTO.learningObjectIdentifier.hruid,
+        learningObjectLanguage: submissionDTO.learningObjectIdentifier.language,
+        learningObjectVersion: submissionDTO.learningObjectIdentifier.version || 1,
+        submitter: submitter,
+        submissionTime: new Date(),
+        content: submissionDTO.content,
+        onBehalfOf: onBehalfOf,
+    });
 }
diff --git a/backend/src/orm.ts b/backend/src/orm.ts
index 3e6e26c8..76cd0ee9 100644
--- a/backend/src/orm.ts
+++ b/backend/src/orm.ts
@@ -1,10 +1,10 @@
-import { EntityManager, MikroORM } from '@mikro-orm/core';
+import { EntityManager, IDatabaseDriver, MikroORM } from '@mikro-orm/core';
 import config from './mikro-orm.config.js';
 import { envVars, getEnvVar } from './util/envVars.js';
 import { getLogger, Logger } from './logging/initalize.js';
 
 let orm: MikroORM | undefined;
-export async function initORM(testingMode = false): Promise<void> {
+export async function initORM(testingMode = false): Promise<MikroORM<IDatabaseDriver, EntityManager>> {
     const logger: Logger = getLogger();
 
     logger.info('Initializing ORM');
@@ -25,6 +25,8 @@ export async function initORM(testingMode = false): Promise<void> {
             );
         }
     }
+
+    return orm;
 }
 export function forkEntityManager(): EntityManager {
     if (!orm) {
diff --git a/backend/src/routes/answers.ts b/backend/src/routes/answers.ts
new file mode 100644
index 00000000..b74f76a0
--- /dev/null
+++ b/backend/src/routes/answers.ts
@@ -0,0 +1,16 @@
+import express from 'express';
+import { createAnswerHandler, deleteAnswerHandler, getAnswerHandler, getAllAnswersHandler, updateAnswerHandler } from '../controllers/answers.js';
+
+const router = express.Router({ mergeParams: true });
+
+router.get('/', getAllAnswersHandler);
+
+router.post('/', createAnswerHandler);
+
+router.get('/:seqAnswer', getAnswerHandler);
+
+router.delete('/:seqAnswer', deleteAnswerHandler);
+
+router.put('/:seqAnswer', updateAnswerHandler);
+
+export default router;
diff --git a/backend/src/routes/assignments.ts b/backend/src/routes/assignments.ts
index 3652dcc6..083ee586 100644
--- a/backend/src/routes/assignments.ts
+++ b/backend/src/routes/assignments.ts
@@ -1,22 +1,26 @@
 import express from 'express';
 import {
     createAssignmentHandler,
+    deleteAssignmentHandler,
     getAllAssignmentsHandler,
     getAssignmentHandler,
     getAssignmentsSubmissionsHandler,
+    putAssignmentHandler,
 } from '../controllers/assignments.js';
 import groupRouter from './groups.js';
 
 const router = express.Router({ mergeParams: true });
 
-// Root endpoint used to search objects
 router.get('/', getAllAssignmentsHandler);
 
 router.post('/', createAssignmentHandler);
 
-// Information about an assignment with id 'id'
 router.get('/:id', getAssignmentHandler);
 
+router.put('/:id', putAssignmentHandler);
+
+router.delete('/:id', deleteAssignmentHandler);
+
 router.get('/:id/submissions', getAssignmentsSubmissionsHandler);
 
 router.get('/:id/questions', (_req, res) => {
diff --git a/backend/src/routes/classes.ts b/backend/src/routes/classes.ts
index e0972988..cef6fd72 100644
--- a/backend/src/routes/classes.ts
+++ b/backend/src/routes/classes.ts
@@ -1,10 +1,17 @@
 import express from 'express';
 import {
+    addClassStudentHandler,
+    addClassTeacherHandler,
     createClassHandler,
+    deleteClassHandler,
+    deleteClassStudentHandler,
+    deleteClassTeacherHandler,
     getAllClassesHandler,
     getClassHandler,
     getClassStudentsHandler,
+    getClassTeachersHandler,
     getTeacherInvitationsHandler,
+    putClassHandler,
 } from '../controllers/classes.js';
 import assignmentRouter from './assignments.js';
 
@@ -15,13 +22,26 @@ router.get('/', getAllClassesHandler);
 
 router.post('/', createClassHandler);
 
-// Information about an class with id 'id'
 router.get('/:id', getClassHandler);
 
+router.put('/:id', putClassHandler);
+
+router.delete('/:id', deleteClassHandler);
+
 router.get('/:id/teacher-invitations', getTeacherInvitationsHandler);
 
 router.get('/:id/students', getClassStudentsHandler);
 
+router.post('/:id/students', addClassStudentHandler);
+
+router.delete('/:id/students/:username', deleteClassStudentHandler);
+
+router.get('/:id/teachers', getClassTeachersHandler);
+
+router.post('/:id/teachers', addClassTeacherHandler);
+
+router.delete('/:id/teachers/:username', deleteClassTeacherHandler);
+
 router.use('/:classid/assignments', assignmentRouter);
 
 export default router;
diff --git a/backend/src/routes/groups.ts b/backend/src/routes/groups.ts
index dc8917bd..7f973972 100644
--- a/backend/src/routes/groups.ts
+++ b/backend/src/routes/groups.ts
@@ -1,5 +1,12 @@
 import express from 'express';
-import { createGroupHandler, getAllGroupsHandler, getGroupHandler, getGroupSubmissionsHandler } from '../controllers/groups.js';
+import {
+    createGroupHandler,
+    deleteGroupHandler,
+    getAllGroupsHandler,
+    getGroupHandler,
+    getGroupSubmissionsHandler,
+    putGroupHandler,
+} from '../controllers/groups.js';
 
 const router = express.Router({ mergeParams: true });
 
@@ -8,16 +15,12 @@ router.get('/', getAllGroupsHandler);
 
 router.post('/', createGroupHandler);
 
-// Information about a group (members, ... [TODO DOC])
 router.get('/:groupid', getGroupHandler);
 
-router.get('/:groupid', getGroupSubmissionsHandler);
+router.put('/:groupid', putGroupHandler);
 
-// The list of questions a group has made
-router.get('/:id/questions', (_req, res) => {
-    res.json({
-        questions: ['0'],
-    });
-});
+router.delete('/:groupid', deleteGroupHandler);
+
+router.get('/:groupid/submissions', getGroupSubmissionsHandler);
 
 export default router;
diff --git a/backend/src/routes/questions.ts b/backend/src/routes/questions.ts
index 31a71f3b..5135c197 100644
--- a/backend/src/routes/questions.ts
+++ b/backend/src/routes/questions.ts
@@ -1,11 +1,7 @@
 import express from 'express';
-import {
-    createQuestionHandler,
-    deleteQuestionHandler,
-    getAllQuestionsHandler,
-    getQuestionAnswersHandler,
-    getQuestionHandler,
-} from '../controllers/questions.js';
+import { createQuestionHandler, deleteQuestionHandler, getAllQuestionsHandler, getQuestionHandler } from '../controllers/questions.js';
+import answerRoutes from './answers.js';
+
 const router = express.Router({ mergeParams: true });
 
 // Query language
@@ -20,6 +16,6 @@ router.delete('/:seq', deleteQuestionHandler);
 // Information about a question with id
 router.get('/:seq', getQuestionHandler);
 
-router.get('/answers/:seq', getQuestionAnswersHandler);
+router.use('/:seq/answers', answerRoutes);
 
 export default router;
diff --git a/backend/src/services/answers.ts b/backend/src/services/answers.ts
new file mode 100644
index 00000000..ab603883
--- /dev/null
+++ b/backend/src/services/answers.ts
@@ -0,0 +1,70 @@
+import { getAnswerRepository } from '../data/repositories.js';
+import { Answer } from '../entities/questions/answer.entity.js';
+import { mapToAnswerDTO, mapToAnswerDTOId } from '../interfaces/answer.js';
+import { fetchTeacher } from './teachers.js';
+import { fetchQuestion } from './questions.js';
+import { QuestionId } from '@dwengo-1/common/interfaces/question';
+import { AnswerData, AnswerDTO, AnswerId } from '@dwengo-1/common/interfaces/answer';
+import { NotFoundException } from '../exceptions/not-found-exception.js';
+
+export async function getAnswersByQuestion(questionId: QuestionId, full: boolean): Promise<AnswerDTO[] | AnswerId[]> {
+    const answerRepository = getAnswerRepository();
+    const question = await fetchQuestion(questionId);
+
+    const answers: Answer[] = await answerRepository.findAllAnswersToQuestion(question);
+
+    if (full) {
+        return answers.map(mapToAnswerDTO);
+    }
+
+    return answers.map(mapToAnswerDTOId);
+}
+
+export async function createAnswer(questionId: QuestionId, answerData: AnswerData): Promise<AnswerDTO> {
+    const answerRepository = getAnswerRepository();
+    const toQuestion = await fetchQuestion(questionId);
+    const author = await fetchTeacher(answerData.author);
+    const content = answerData.content;
+
+    const answer = await answerRepository.createAnswer({
+        toQuestion,
+        author,
+        content,
+    });
+    return mapToAnswerDTO(answer);
+}
+
+async function fetchAnswer(questionId: QuestionId, sequenceNumber: number): Promise<Answer> {
+    const answerRepository = getAnswerRepository();
+    const question = await fetchQuestion(questionId);
+    const answer = await answerRepository.findAnswer(question, sequenceNumber);
+
+    if (!answer) {
+        throw new NotFoundException('Answer with questionID and sequence number not found');
+    }
+
+    return answer;
+}
+
+export async function getAnswer(questionId: QuestionId, sequenceNumber: number): Promise<AnswerDTO> {
+    const answer = await fetchAnswer(questionId, sequenceNumber);
+    return mapToAnswerDTO(answer);
+}
+
+export async function deleteAnswer(questionId: QuestionId, sequenceNumber: number): Promise<AnswerDTO> {
+    const answerRepository = getAnswerRepository();
+
+    const question = await fetchQuestion(questionId);
+    const answer = await fetchAnswer(questionId, sequenceNumber);
+
+    await answerRepository.removeAnswerByQuestionAndSequenceNumber(question, sequenceNumber);
+    return mapToAnswerDTO(answer);
+}
+
+export async function updateAnswer(questionId: QuestionId, sequenceNumber: number, answerData: AnswerData): Promise<AnswerDTO> {
+    const answerRepository = getAnswerRepository();
+    const answer = await fetchAnswer(questionId, sequenceNumber);
+
+    const newAnswer = await answerRepository.updateContent(answer, answerData.content);
+    return mapToAnswerDTO(newAnswer);
+}
diff --git a/backend/src/services/assignments.ts b/backend/src/services/assignments.ts
index e86b69b2..5fd8f67f 100644
--- a/backend/src/services/assignments.ts
+++ b/backend/src/services/assignments.ts
@@ -1,18 +1,43 @@
-import { getAssignmentRepository, getClassRepository, getGroupRepository, getSubmissionRepository } from '../data/repositories.js';
-import { mapToAssignment, mapToAssignmentDTO, mapToAssignmentDTOId } from '../interfaces/assignment.js';
-import { mapToSubmissionDTO, mapToSubmissionDTOId } from '../interfaces/submission.js';
 import { AssignmentDTO } from '@dwengo-1/common/interfaces/assignment';
+import {
+    getAssignmentRepository,
+    getClassRepository,
+    getGroupRepository,
+    getQuestionRepository,
+    getSubmissionRepository,
+} from '../data/repositories.js';
+import { Assignment } from '../entities/assignments/assignment.entity.js';
+import { NotFoundException } from '../exceptions/not-found-exception.js';
+import { mapToAssignment, mapToAssignmentDTO, mapToAssignmentDTOId } from '../interfaces/assignment.js';
+import { mapToQuestionDTO } from '../interfaces/question.js';
+import { mapToSubmissionDTO, mapToSubmissionDTOId } from '../interfaces/submission.js';
+import { fetchClass } from './classes.js';
+import { QuestionDTO, QuestionId } from '@dwengo-1/common/interfaces/question';
 import { SubmissionDTO, SubmissionDTOId } from '@dwengo-1/common/interfaces/submission';
-import { getLogger } from '../logging/initalize.js';
+import { EntityDTO } from '@mikro-orm/core';
+import { putObject } from './service-helper.js';
 
-export async function getAllAssignments(classid: string, full: boolean): Promise<AssignmentDTO[]> {
+export async function fetchAssignment(classid: string, assignmentNumber: number): Promise<Assignment> {
     const classRepository = getClassRepository();
     const cls = await classRepository.findById(classid);
 
     if (!cls) {
-        return [];
+        throw new NotFoundException("Could not find assignment's class");
     }
 
+    const assignmentRepository = getAssignmentRepository();
+    const assignment = await assignmentRepository.findByClassAndId(cls, assignmentNumber);
+
+    if (!assignment) {
+        throw new NotFoundException('Could not find assignment');
+    }
+
+    return assignment;
+}
+
+export async function getAllAssignments(classid: string, full: boolean): Promise<AssignmentDTO[]> {
+    const cls = await fetchClass(classid);
+
     const assignmentRepository = getAssignmentRepository();
     const assignments = await assignmentRepository.findAllAssignmentsInClass(cls);
 
@@ -23,42 +48,37 @@ export async function getAllAssignments(classid: string, full: boolean): Promise
     return assignments.map(mapToAssignmentDTOId);
 }
 
-export async function createAssignment(classid: string, assignmentData: AssignmentDTO): Promise<AssignmentDTO | null> {
-    const classRepository = getClassRepository();
-    const cls = await classRepository.findById(classid);
-
-    if (!cls) {
-        return null;
-    }
+export async function createAssignment(classid: string, assignmentData: AssignmentDTO): Promise<AssignmentDTO> {
+    const cls = await fetchClass(classid);
 
     const assignment = mapToAssignment(assignmentData, cls);
+
     const assignmentRepository = getAssignmentRepository();
+    const newAssignment = assignmentRepository.create(assignment);
+    await assignmentRepository.save(newAssignment, { preventOverwrite: true });
 
-    try {
-        const newAssignment = assignmentRepository.create(assignment);
-        await assignmentRepository.save(newAssignment);
-
-        return mapToAssignmentDTO(newAssignment);
-    } catch (e) {
-        getLogger().error(e);
-        return null;
-    }
+    return mapToAssignmentDTO(newAssignment);
 }
 
-export async function getAssignment(classid: string, id: number): Promise<AssignmentDTO | null> {
-    const classRepository = getClassRepository();
-    const cls = await classRepository.findById(classid);
+export async function getAssignment(classid: string, id: number): Promise<AssignmentDTO> {
+    const assignment = await fetchAssignment(classid, id);
+    return mapToAssignmentDTO(assignment);
+}
 
-    if (!cls) {
-        return null;
-    }
+export async function putAssignment(classid: string, id: number, assignmentData: Partial<EntityDTO<Assignment>>): Promise<AssignmentDTO> {
+    const assignment = await fetchAssignment(classid, id);
+
+    await putObject<Assignment>(assignment, assignmentData, getAssignmentRepository());
+
+    return mapToAssignmentDTO(assignment);
+}
+
+export async function deleteAssignment(classid: string, id: number): Promise<AssignmentDTO> {
+    const assignment = await fetchAssignment(classid, id);
+    const cls = await fetchClass(classid);
 
     const assignmentRepository = getAssignmentRepository();
-    const assignment = await assignmentRepository.findByClassAndId(cls, id);
-
-    if (!assignment) {
-        return null;
-    }
+    await assignmentRepository.deleteByClassAndId(cls, id);
 
     return mapToAssignmentDTO(assignment);
 }
@@ -68,19 +88,7 @@ export async function getAssignmentsSubmissions(
     assignmentNumber: number,
     full: boolean
 ): Promise<SubmissionDTO[] | SubmissionDTOId[]> {
-    const classRepository = getClassRepository();
-    const cls = await classRepository.findById(classid);
-
-    if (!cls) {
-        return [];
-    }
-
-    const assignmentRepository = getAssignmentRepository();
-    const assignment = await assignmentRepository.findByClassAndId(cls, assignmentNumber);
-
-    if (!assignment) {
-        return [];
-    }
+    const assignment = await fetchAssignment(classid, assignmentNumber);
 
     const groupRepository = getGroupRepository();
     const groups = await groupRepository.findAllGroupsForAssignment(assignment);
@@ -94,3 +102,16 @@ export async function getAssignmentsSubmissions(
 
     return submissions.map(mapToSubmissionDTOId);
 }
+
+export async function getAssignmentsQuestions(classid: string, assignmentNumber: number, full: boolean): Promise<QuestionDTO[] | QuestionId[]> {
+    const assignment = await fetchAssignment(classid, assignmentNumber);
+
+    const questionRepository = getQuestionRepository();
+    const questions = await questionRepository.findAllByAssignment(assignment);
+
+    if (full) {
+        return questions.map(mapToQuestionDTO);
+    }
+
+    return questions.map(mapToQuestionDTO);
+}
diff --git a/backend/src/services/classes.ts b/backend/src/services/classes.ts
index 754277cf..1f197b2a 100644
--- a/backend/src/services/classes.ts
+++ b/backend/src/services/classes.ts
@@ -1,22 +1,25 @@
-import { getClassRepository, getStudentRepository, getTeacherInvitationRepository, getTeacherRepository } from '../data/repositories.js';
+import { getClassRepository, getTeacherInvitationRepository } from '../data/repositories.js';
 import { mapToClassDTO } from '../interfaces/class.js';
 import { mapToStudentDTO } from '../interfaces/student.js';
 import { mapToTeacherInvitationDTO, mapToTeacherInvitationDTOIds } from '../interfaces/teacher-invitation.js';
-import { getLogger } from '../logging/initalize.js';
 import { NotFoundException } from '../exceptions/not-found-exception.js';
 import { Class } from '../entities/classes/class.entity.js';
 import { ClassDTO } from '@dwengo-1/common/interfaces/class';
 import { TeacherInvitationDTO } from '@dwengo-1/common/interfaces/teacher-invitation';
 import { StudentDTO } from '@dwengo-1/common/interfaces/student';
+import { fetchTeacher } from './teachers.js';
+import { fetchStudent } from './students.js';
+import { TeacherDTO } from '@dwengo-1/common/interfaces/teacher';
+import { mapToTeacherDTO } from '../interfaces/teacher.js';
+import { EntityDTO } from '@mikro-orm/core';
+import { putObject } from './service-helper.js';
 
-const logger = getLogger();
-
-export async function fetchClass(classId: string): Promise<Class> {
+export async function fetchClass(classid: string): Promise<Class> {
     const classRepository = getClassRepository();
-    const cls = await classRepository.findById(classId);
+    const cls = await classRepository.findById(classid);
 
     if (!cls) {
-        throw new NotFoundException('Class with id not found');
+        throw new NotFoundException('Class not found');
     }
 
     return cls;
@@ -24,11 +27,7 @@ export async function fetchClass(classId: string): Promise<Class> {
 
 export async function getAllClasses(full: boolean): Promise<ClassDTO[] | string[]> {
     const classRepository = getClassRepository();
-    const classes = await classRepository.find({}, { populate: ['students', 'teachers'] });
-
-    if (!classes) {
-        return [];
-    }
+    const classes = await classRepository.findAll({ populate: ['students', 'teachers'] });
 
     if (full) {
         return classes.map(mapToClassDTO);
@@ -36,74 +35,71 @@ export async function getAllClasses(full: boolean): Promise<ClassDTO[] | string[
     return classes.map((cls) => cls.classId!);
 }
 
-export async function createClass(classData: ClassDTO): Promise<ClassDTO | null> {
-    const teacherRepository = getTeacherRepository();
-    const teacherUsernames = classData.teachers || [];
-    const teachers = (await Promise.all(teacherUsernames.map(async (id) => teacherRepository.findByUsername(id)))).filter(
-        (teacher) => teacher !== null
-    );
-
-    const studentRepository = getStudentRepository();
-    const studentUsernames = classData.students || [];
-    const students = (await Promise.all(studentUsernames.map(async (id) => studentRepository.findByUsername(id)))).filter(
-        (student) => student !== null
-    );
-
-    const classRepository = getClassRepository();
-
-    try {
-        const newClass = classRepository.create({
-            displayName: classData.displayName,
-            teachers: teachers,
-            students: students,
-        });
-        await classRepository.save(newClass);
-
-        return mapToClassDTO(newClass);
-    } catch (e) {
-        logger.error(e);
-        return null;
-    }
+export async function getClass(classId: string): Promise<ClassDTO> {
+    const cls = await fetchClass(classId);
+    return mapToClassDTO(cls);
 }
 
-export async function getClass(classId: string): Promise<ClassDTO | null> {
-    const classRepository = getClassRepository();
-    const cls = await classRepository.findById(classId);
+export async function createClass(classData: ClassDTO): Promise<ClassDTO> {
+    const teacherUsernames = classData.teachers || [];
+    const teachers = await Promise.all(teacherUsernames.map(async (id) => fetchTeacher(id)));
 
-    if (!cls) {
-        return null;
-    }
+    const studentUsernames = classData.students || [];
+    const students = await Promise.all(studentUsernames.map(async (id) => fetchStudent(id)));
+
+    const classRepository = getClassRepository();
+    const newClass = classRepository.create({
+        displayName: classData.displayName,
+        teachers: teachers,
+        students: students,
+    });
+    await classRepository.save(newClass, { preventOverwrite: true });
+
+    return mapToClassDTO(newClass);
+}
+
+export async function putClass(classId: string, classData: Partial<EntityDTO<Class>>): Promise<ClassDTO> {
+    const cls = await fetchClass(classId);
+
+    await putObject<Class>(cls, classData, getClassRepository());
 
     return mapToClassDTO(cls);
 }
 
-async function fetchClassStudents(classId: string): Promise<StudentDTO[]> {
+export async function deleteClass(classId: string): Promise<ClassDTO> {
+    const cls = await fetchClass(classId);
+
     const classRepository = getClassRepository();
-    const cls = await classRepository.findById(classId);
+    await classRepository.deleteById(classId);
 
-    if (!cls) {
-        return [];
+    return mapToClassDTO(cls);
+}
+
+export async function getClassStudents(classId: string, full: boolean): Promise<StudentDTO[] | string[]> {
+    const cls = await fetchClass(classId);
+
+    if (full) {
+        return cls.students.map(mapToStudentDTO);
     }
+    return cls.students.map((student) => student.username);
+}
 
+export async function getClassStudentsDTO(classId: string): Promise<StudentDTO[]> {
+    const cls = await fetchClass(classId);
     return cls.students.map(mapToStudentDTO);
 }
 
-export async function getClassStudents(classId: string): Promise<StudentDTO[]> {
-    return await fetchClassStudents(classId);
-}
+export async function getClassTeachers(classId: string, full: boolean): Promise<TeacherDTO[] | string[]> {
+    const cls = await fetchClass(classId);
 
-export async function getClassStudentsIds(classId: string): Promise<string[]> {
-    const students: StudentDTO[] = await fetchClassStudents(classId);
-    return students.map((student) => student.username);
+    if (full) {
+        return cls.teachers.map(mapToTeacherDTO);
+    }
+    return cls.teachers.map((student) => student.username);
 }
 
 export async function getClassTeacherInvitations(classId: string, full: boolean): Promise<TeacherInvitationDTO[]> {
-    const classRepository = getClassRepository();
-    const cls = await classRepository.findById(classId);
-
-    if (!cls) {
-        return [];
-    }
+    const cls = await fetchClass(classId);
 
     const teacherInvitationRepository = getTeacherInvitationRepository();
     const invitations = await teacherInvitationRepository.findAllInvitationsForClass(cls);
@@ -114,3 +110,41 @@ export async function getClassTeacherInvitations(classId: string, full: boolean)
 
     return invitations.map(mapToTeacherInvitationDTOIds);
 }
+
+export async function deleteClassStudent(classId: string, username: string): Promise<ClassDTO> {
+    const cls = await fetchClass(classId);
+
+    const newStudents = { students: cls.students.filter((student) => student.username !== username) };
+    await putObject<Class>(cls, newStudents, getClassRepository());
+
+    return mapToClassDTO(cls);
+}
+
+export async function deleteClassTeacher(classId: string, username: string): Promise<ClassDTO> {
+    const cls = await fetchClass(classId);
+
+    const newTeachers = { teachers: cls.teachers.filter((teacher) => teacher.username !== username) };
+    await putObject<Class>(cls, newTeachers, getClassRepository());
+
+    return mapToClassDTO(cls);
+}
+
+export async function addClassStudent(classId: string, username: string): Promise<ClassDTO> {
+    const cls = await fetchClass(classId);
+    const newStudent = await fetchStudent(username);
+
+    const newStudents = { students: [...cls.students, newStudent] };
+    await putObject<Class>(cls, newStudents, getClassRepository());
+
+    return mapToClassDTO(cls);
+}
+
+export async function addClassTeacher(classId: string, username: string): Promise<ClassDTO> {
+    const cls = await fetchClass(classId);
+    const newTeacher = await fetchTeacher(username);
+
+    const newTeachers = { teachers: [...cls.teachers, newTeacher] };
+    await putObject<Class>(cls, newTeachers, getClassRepository());
+
+    return mapToClassDTO(cls);
+}
diff --git a/backend/src/services/groups.ts b/backend/src/services/groups.ts
index b009e772..3c6f2919 100644
--- a/backend/src/services/groups.ts
+++ b/backend/src/services/groups.ts
@@ -1,105 +1,90 @@
-import {
-    getAssignmentRepository,
-    getClassRepository,
-    getGroupRepository,
-    getStudentRepository,
-    getSubmissionRepository,
-} from '../data/repositories.js';
+import { EntityDTO } from '@mikro-orm/core';
+import { getGroupRepository, getStudentRepository, getSubmissionRepository } from '../data/repositories.js';
 import { Group } from '../entities/assignments/group.entity.js';
 import { mapToGroupDTO, mapToShallowGroupDTO } from '../interfaces/group.js';
 import { mapToSubmissionDTO, mapToSubmissionDTOId } from '../interfaces/submission.js';
 import { GroupDTO } from '@dwengo-1/common/interfaces/group';
 import { SubmissionDTO, SubmissionDTOId } from '@dwengo-1/common/interfaces/submission';
-import { getLogger } from '../logging/initalize.js';
+import { fetchAssignment } from './assignments.js';
+import { NotFoundException } from '../exceptions/not-found-exception.js';
+import { putObject } from './service-helper.js';
 
-export async function getGroup(classId: string, assignmentNumber: number, groupNumber: number, full: boolean): Promise<GroupDTO | null> {
-    const classRepository = getClassRepository();
-    const cls = await classRepository.findById(classId);
-
-    if (!cls) {
-        return null;
-    }
-
-    const assignmentRepository = getAssignmentRepository();
-    const assignment = await assignmentRepository.findByClassAndId(cls, assignmentNumber);
-
-    if (!assignment) {
-        return null;
-    }
+export async function fetchGroup(classId: string, assignmentNumber: number, groupNumber: number): Promise<Group> {
+    const assignment = await fetchAssignment(classId, assignmentNumber);
 
     const groupRepository = getGroupRepository();
     const group = await groupRepository.findByAssignmentAndGroupNumber(assignment, groupNumber);
 
     if (!group) {
-        return null;
+        throw new NotFoundException('Could not find group');
     }
 
-    if (full) {
-        return mapToGroupDTO(group);
-    }
-
-    return mapToShallowGroupDTO(group);
+    return group;
 }
 
-export async function createGroup(groupData: GroupDTO, classid: string, assignmentNumber: number): Promise<Group | null> {
+export async function getGroup(classId: string, assignmentNumber: number, groupNumber: number): Promise<GroupDTO> {
+    const group = await fetchGroup(classId, assignmentNumber, groupNumber);
+    return mapToGroupDTO(group);
+}
+
+export async function putGroup(
+    classId: string,
+    assignmentNumber: number,
+    groupNumber: number,
+    groupData: Partial<EntityDTO<Group>>
+): Promise<GroupDTO> {
+    const group = await fetchGroup(classId, assignmentNumber, groupNumber);
+
+    await putObject<Group>(group, groupData, getGroupRepository());
+
+    return mapToGroupDTO(group);
+}
+
+export async function deleteGroup(classId: string, assignmentNumber: number, groupNumber: number): Promise<GroupDTO> {
+    const group = await fetchGroup(classId, assignmentNumber, groupNumber);
+    const assignment = await fetchAssignment(classId, assignmentNumber);
+
+    const groupRepository = getGroupRepository();
+    await groupRepository.deleteByAssignmentAndGroupNumber(assignment, groupNumber);
+
+    return mapToGroupDTO(group);
+}
+
+export async function getExistingGroupFromGroupDTO(groupData: GroupDTO): Promise<Group> {
+    const classId = typeof groupData.class === 'string' ? groupData.class : groupData.class.id;
+    const assignmentNumber = typeof groupData.assignment === 'number' ? groupData.assignment : groupData.assignment.id;
+    const groupNumber = groupData.groupNumber;
+
+    return await fetchGroup(classId, assignmentNumber, groupNumber);
+}
+
+export async function createGroup(groupData: GroupDTO, classid: string, assignmentNumber: number): Promise<GroupDTO> {
     const studentRepository = getStudentRepository();
 
-    const memberUsernames = (groupData.members as string[]) || []; // TODO check if groupdata.members is a list
+    const memberUsernames = (groupData.members as string[]) || [];
     const members = (await Promise.all([...memberUsernames].map(async (id) => studentRepository.findByUsername(id)))).filter(
         (student) => student !== null
     );
 
-    getLogger().debug(members);
-
-    const classRepository = getClassRepository();
-    const cls = await classRepository.findById(classid);
-
-    if (!cls) {
-        return null;
-    }
-
-    const assignmentRepository = getAssignmentRepository();
-    const assignment = await assignmentRepository.findByClassAndId(cls, assignmentNumber);
-
-    if (!assignment) {
-        return null;
-    }
+    const assignment = await fetchAssignment(classid, assignmentNumber);
 
     const groupRepository = getGroupRepository();
-    try {
-        const newGroup = groupRepository.create({
-            assignment: assignment,
-            members: members,
-        });
-        await groupRepository.save(newGroup);
+    const newGroup = groupRepository.create({
+        assignment: assignment,
+        members: members,
+    });
+    await groupRepository.save(newGroup);
 
-        return newGroup;
-    } catch (e) {
-        getLogger().error(e);
-        return null;
-    }
+    return mapToGroupDTO(newGroup);
 }
 
 export async function getAllGroups(classId: string, assignmentNumber: number, full: boolean): Promise<GroupDTO[]> {
-    const classRepository = getClassRepository();
-    const cls = await classRepository.findById(classId);
-
-    if (!cls) {
-        return [];
-    }
-
-    const assignmentRepository = getAssignmentRepository();
-    const assignment = await assignmentRepository.findByClassAndId(cls, assignmentNumber);
-
-    if (!assignment) {
-        return [];
-    }
+    const assignment = await fetchAssignment(classId, assignmentNumber);
 
     const groupRepository = getGroupRepository();
     const groups = await groupRepository.findAllGroupsForAssignment(assignment);
 
     if (full) {
-        getLogger().debug({ full: full, groups: groups });
         return groups.map(mapToGroupDTO);
     }
 
@@ -112,26 +97,7 @@ export async function getGroupSubmissions(
     groupNumber: number,
     full: boolean
 ): Promise<SubmissionDTO[] | SubmissionDTOId[]> {
-    const classRepository = getClassRepository();
-    const cls = await classRepository.findById(classId);
-
-    if (!cls) {
-        return [];
-    }
-
-    const assignmentRepository = getAssignmentRepository();
-    const assignment = await assignmentRepository.findByClassAndId(cls, assignmentNumber);
-
-    if (!assignment) {
-        return [];
-    }
-
-    const groupRepository = getGroupRepository();
-    const group = await groupRepository.findByAssignmentAndGroupNumber(assignment, groupNumber);
-
-    if (!group) {
-        return [];
-    }
+    const group = await fetchGroup(classId, assignmentNumber, groupNumber);
 
     const submissionRepository = getSubmissionRepository();
     const submissions = await submissionRepository.findAllSubmissionsForGroup(group);
diff --git a/backend/src/services/learning-objects/attachment-service.ts b/backend/src/services/learning-objects/attachment-service.ts
index 46fc5e03..2a6298c1 100644
--- a/backend/src/services/learning-objects/attachment-service.ts
+++ b/backend/src/services/learning-objects/attachment-service.ts
@@ -1,10 +1,10 @@
 import { getAttachmentRepository } from '../../data/repositories.js';
 import { Attachment } from '../../entities/content/attachment.entity.js';
 
-import { LearningObjectIdentifier } from '@dwengo-1/common/interfaces/learning-content';
+import { LearningObjectIdentifierDTO } from '@dwengo-1/common/interfaces/learning-content';
 
 const attachmentService = {
-    async getAttachment(learningObjectId: LearningObjectIdentifier, attachmentName: string): Promise<Attachment | null> {
+    async getAttachment(learningObjectId: LearningObjectIdentifierDTO, attachmentName: string): Promise<Attachment | null> {
         const attachmentRepo = getAttachmentRepository();
 
         if (learningObjectId.version) {
diff --git a/backend/src/services/learning-objects/database-learning-object-provider.ts b/backend/src/services/learning-objects/database-learning-object-provider.ts
index 361153f5..fa278bba 100644
--- a/backend/src/services/learning-objects/database-learning-object-provider.ts
+++ b/backend/src/services/learning-objects/database-learning-object-provider.ts
@@ -6,7 +6,7 @@ import processingService from './processing/processing-service.js';
 import { NotFoundError } from '@mikro-orm/core';
 import learningObjectService from './learning-object-service.js';
 import { getLogger, Logger } from '../../logging/initalize.js';
-import { FilteredLearningObject, LearningObjectIdentifier, LearningPathIdentifier } from '@dwengo-1/common/interfaces/learning-content';
+import { FilteredLearningObject, LearningObjectIdentifierDTO, LearningPathIdentifier } from '@dwengo-1/common/interfaces/learning-content';
 
 const logger: Logger = getLogger();
 
@@ -40,7 +40,7 @@ function convertLearningObject(learningObject: LearningObject | null): FilteredL
     };
 }
 
-async function findLearningObjectEntityById(id: LearningObjectIdentifier): Promise<LearningObject | null> {
+async function findLearningObjectEntityById(id: LearningObjectIdentifierDTO): Promise<LearningObject | null> {
     const learningObjectRepo = getLearningObjectRepository();
 
     return learningObjectRepo.findLatestByHruidAndLanguage(id.hruid, id.language);
@@ -53,7 +53,7 @@ const databaseLearningObjectProvider: LearningObjectProvider = {
     /**
      * Fetches a single learning object by its HRUID
      */
-    async getLearningObjectById(id: LearningObjectIdentifier): Promise<FilteredLearningObject | null> {
+    async getLearningObjectById(id: LearningObjectIdentifierDTO): Promise<FilteredLearningObject | null> {
         const learningObject = await findLearningObjectEntityById(id);
         return convertLearningObject(learningObject);
     },
@@ -61,7 +61,7 @@ const databaseLearningObjectProvider: LearningObjectProvider = {
     /**
      * Obtain a HTML-rendering of the learning object with the given identifier (as a string).
      */
-    async getLearningObjectHTML(id: LearningObjectIdentifier): Promise<string | null> {
+    async getLearningObjectHTML(id: LearningObjectIdentifierDTO): Promise<string | null> {
         const learningObjectRepo = getLearningObjectRepository();
 
         const learningObject = await learningObjectRepo.findLatestByHruidAndLanguage(id.hruid, id.language);
diff --git a/backend/src/services/learning-objects/dwengo-api-learning-object-provider.ts b/backend/src/services/learning-objects/dwengo-api-learning-object-provider.ts
index d67b69ae..e9898f62 100644
--- a/backend/src/services/learning-objects/dwengo-api-learning-object-provider.ts
+++ b/backend/src/services/learning-objects/dwengo-api-learning-object-provider.ts
@@ -5,7 +5,7 @@ import { LearningObjectProvider } from './learning-object-provider.js';
 import { getLogger, Logger } from '../../logging/initalize.js';
 import {
     FilteredLearningObject,
-    LearningObjectIdentifier,
+    LearningObjectIdentifierDTO,
     LearningObjectMetadata,
     LearningObjectNode,
     LearningPathIdentifier,
@@ -67,7 +67,7 @@ async function fetchLearningObjects(learningPathId: LearningPathIdentifier, full
 
         const objects = await Promise.all(
             nodes.map(async (node) => {
-                const learningObjectId: LearningObjectIdentifier = {
+                const learningObjectId: LearningObjectIdentifierDTO = {
                     hruid: node.learningobject_hruid,
                     language: learningPathId.language,
                 };
@@ -85,7 +85,7 @@ const dwengoApiLearningObjectProvider: LearningObjectProvider = {
     /**
      * Fetches a single learning object by its HRUID
      */
-    async getLearningObjectById(id: LearningObjectIdentifier): Promise<FilteredLearningObject | null> {
+    async getLearningObjectById(id: LearningObjectIdentifierDTO): Promise<FilteredLearningObject | null> {
         const metadataUrl = `${DWENGO_API_BASE}/learningObject/getMetadata`;
         const metadata = await fetchWithLogging<LearningObjectMetadata>(
             metadataUrl,
@@ -121,7 +121,7 @@ const dwengoApiLearningObjectProvider: LearningObjectProvider = {
      * Obtain a HTML-rendering of the learning object with the given identifier (as a string). For learning objects
      * from the Dwengo API, this means passing through the HTML rendering from there.
      */
-    async getLearningObjectHTML(id: LearningObjectIdentifier): Promise<string | null> {
+    async getLearningObjectHTML(id: LearningObjectIdentifierDTO): Promise<string | null> {
         const htmlUrl = `${DWENGO_API_BASE}/learningObject/getRaw`;
         const html = await fetchWithLogging<string>(htmlUrl, `Metadata for Learning Object HRUID "${id.hruid}" (language ${id.language})`, {
             params: { ...id },
diff --git a/backend/src/services/learning-objects/learning-object-provider.ts b/backend/src/services/learning-objects/learning-object-provider.ts
index a0fcb552..14848bc0 100644
--- a/backend/src/services/learning-objects/learning-object-provider.ts
+++ b/backend/src/services/learning-objects/learning-object-provider.ts
@@ -1,10 +1,10 @@
-import { FilteredLearningObject, LearningObjectIdentifier, LearningPathIdentifier } from '@dwengo-1/common/interfaces/learning-content';
+import { FilteredLearningObject, LearningObjectIdentifierDTO, LearningPathIdentifier } from '@dwengo-1/common/interfaces/learning-content';
 
 export interface LearningObjectProvider {
     /**
      * Fetches a single learning object by its HRUID
      */
-    getLearningObjectById(id: LearningObjectIdentifier): Promise<FilteredLearningObject | null>;
+    getLearningObjectById(id: LearningObjectIdentifierDTO): Promise<FilteredLearningObject | null>;
 
     /**
      * Fetch full learning object data (metadata)
@@ -19,5 +19,5 @@ export interface LearningObjectProvider {
     /**
      * Obtain a HTML-rendering of the learning object with the given identifier (as a string).
      */
-    getLearningObjectHTML(id: LearningObjectIdentifier): Promise<string | null>;
+    getLearningObjectHTML(id: LearningObjectIdentifierDTO): Promise<string | null>;
 }
diff --git a/backend/src/services/learning-objects/learning-object-service.ts b/backend/src/services/learning-objects/learning-object-service.ts
index 5a06f0f2..7b4f47fc 100644
--- a/backend/src/services/learning-objects/learning-object-service.ts
+++ b/backend/src/services/learning-objects/learning-object-service.ts
@@ -2,9 +2,9 @@ import dwengoApiLearningObjectProvider from './dwengo-api-learning-object-provid
 import { LearningObjectProvider } from './learning-object-provider.js';
 import { envVars, getEnvVar } from '../../util/envVars.js';
 import databaseLearningObjectProvider from './database-learning-object-provider.js';
-import { FilteredLearningObject, LearningObjectIdentifier, LearningPathIdentifier } from '@dwengo-1/common/interfaces/learning-content';
+import { FilteredLearningObject, LearningObjectIdentifierDTO, LearningPathIdentifier } from '@dwengo-1/common/interfaces/learning-content';
 
-function getProvider(id: LearningObjectIdentifier): LearningObjectProvider {
+function getProvider(id: LearningObjectIdentifierDTO): LearningObjectProvider {
     if (id.hruid.startsWith(getEnvVar(envVars.UserContentPrefix))) {
         return databaseLearningObjectProvider;
     }
@@ -18,7 +18,7 @@ const learningObjectService = {
     /**
      * Fetches a single learning object by its HRUID
      */
-    async getLearningObjectById(id: LearningObjectIdentifier): Promise<FilteredLearningObject | null> {
+    async getLearningObjectById(id: LearningObjectIdentifierDTO): Promise<FilteredLearningObject | null> {
         return getProvider(id).getLearningObjectById(id);
     },
 
@@ -39,7 +39,7 @@ const learningObjectService = {
     /**
      * Obtain a HTML-rendering of the learning object with the given identifier (as a string).
      */
-    async getLearningObjectHTML(id: LearningObjectIdentifier): Promise<string | null> {
+    async getLearningObjectHTML(id: LearningObjectIdentifierDTO): Promise<string | null> {
         return getProvider(id).getLearningObjectHTML(id);
     },
 };
diff --git a/backend/src/services/learning-objects/processing/markdown/dwengo-marked-renderer.ts b/backend/src/services/learning-objects/processing/markdown/dwengo-marked-renderer.ts
index 87ba13b7..e01d8ed6 100644
--- a/backend/src/services/learning-objects/processing/markdown/dwengo-marked-renderer.ts
+++ b/backend/src/services/learning-objects/processing/markdown/dwengo-marked-renderer.ts
@@ -12,7 +12,7 @@ import Image = marked.Tokens.Image;
 import Heading = marked.Tokens.Heading;
 import Link = marked.Tokens.Link;
 import RendererObject = marked.RendererObject;
-import { LearningObjectIdentifier } from '@dwengo-1/common/interfaces/learning-content';
+import { LearningObjectIdentifierDTO } from '@dwengo-1/common/interfaces/learning-content';
 import { Language } from '@dwengo-1/common/util/language';
 
 const prefixes = {
@@ -25,7 +25,7 @@ const prefixes = {
     blockly: '@blockly',
 };
 
-function extractLearningObjectIdFromHref(href: string): LearningObjectIdentifier {
+function extractLearningObjectIdFromHref(href: string): LearningObjectIdentifierDTO {
     const [hruid, language, version] = href.split(/\/(.+)/, 2)[1].split('/');
     return {
         hruid,
diff --git a/backend/src/services/learning-objects/processing/processing-service.ts b/backend/src/services/learning-objects/processing/processing-service.ts
index e9147e31..61821d80 100644
--- a/backend/src/services/learning-objects/processing/processing-service.ts
+++ b/backend/src/services/learning-objects/processing/processing-service.ts
@@ -14,7 +14,7 @@ import { LearningObject } from '../../../entities/content/learning-object.entity
 import Processor from './processor.js';
 import { DwengoContentType } from './content-type.js';
 import { replaceAsync } from '../../../util/async.js';
-import { LearningObjectIdentifier } from '@dwengo-1/common/interfaces/learning-content';
+import { LearningObjectIdentifierDTO } from '@dwengo-1/common/interfaces/learning-content';
 import { Language } from '@dwengo-1/common/util/language';
 
 const EMBEDDED_LEARNING_OBJECT_PLACEHOLDER = /<learning-object hruid="([^"]+)" language="([^"]+)" version="([^"]+)"\/>/g;
@@ -50,7 +50,7 @@ class ProcessingService {
      */
     async render(
         learningObject: LearningObject,
-        fetchEmbeddedLearningObjects?: (loId: LearningObjectIdentifier) => Promise<LearningObject | null>
+        fetchEmbeddedLearningObjects?: (loId: LearningObjectIdentifierDTO) => Promise<LearningObject | null>
     ): Promise<string> {
         const html = this.processors.get(learningObject.contentType)!.renderLearningObject(learningObject);
         if (fetchEmbeddedLearningObjects) {
diff --git a/backend/src/services/questions.ts b/backend/src/services/questions.ts
index 4794a3dc..889c6da6 100644
--- a/backend/src/services/questions.ts
+++ b/backend/src/services/questions.ts
@@ -1,15 +1,17 @@
 import { getAnswerRepository, getAssignmentRepository, getClassRepository, getGroupRepository, getQuestionRepository } from '../data/repositories.js';
-import { mapToQuestionDTO, mapToQuestionDTOId } from '../interfaces/question.js';
+import {mapToLearningObjectID, mapToQuestionDTO, mapToQuestionDTOId} from '../interfaces/question.js';
 import { Question } from '../entities/questions/question.entity.js';
 import { Answer } from '../entities/questions/answer.entity.js';
 import { mapToAnswerDTO, mapToAnswerDTOId } from '../interfaces/answer.js';
 import { QuestionRepository } from '../data/questions/question-repository.js';
 import { LearningObjectIdentifier } from '../entities/content/learning-object-identifier.js';
-import { mapToStudent } from '../interfaces/student.js';
-import { QuestionDTO, QuestionId } from '@dwengo-1/common/interfaces/question';
+import {QuestionData, QuestionDTO, QuestionId} from '@dwengo-1/common/interfaces/question';
 import { AnswerDTO, AnswerId } from '@dwengo-1/common/interfaces/answer';
-import { AssignmentDTO } from '@dwengo-1/common/interfaces/assignment';
 import { mapToAssignment } from '../interfaces/assignment.js';
+import {AssignmentDTO} from "@dwengo-1/common/interfaces/assignment";
+import { fetchStudent } from './students.js';
+import {NotFoundException} from "../exceptions/not-found-exception";
+import { FALLBACK_VERSION_NUM } from '../config.js';
 
 export async function getQuestionsAboutLearningObjectInAssignment(
     loId: LearningObjectIdentifier,
@@ -32,10 +34,6 @@ export async function getAllQuestions(id: LearningObjectIdentifier, full: boolea
     const questionRepository: QuestionRepository = getQuestionRepository();
     const questions = await questionRepository.findAllQuestionsAboutLearningObject(id);
 
-    if (!questions) {
-        return [];
-    }
-
     if (full) {
         return questions.map(mapToQuestionDTO);
     }
@@ -43,24 +41,22 @@ export async function getAllQuestions(id: LearningObjectIdentifier, full: boolea
     return questions.map(mapToQuestionDTOId);
 }
 
-async function fetchQuestion(questionId: QuestionId): Promise<Question | null> {
+export async function fetchQuestion(questionId: QuestionId): Promise<Question> {
     const questionRepository = getQuestionRepository();
-
-    return await questionRepository.findOne({
-        learningObjectHruid: questionId.learningObjectIdentifier.hruid,
-        learningObjectLanguage: questionId.learningObjectIdentifier.language,
-        learningObjectVersion: questionId.learningObjectIdentifier.version,
-        sequenceNumber: questionId.sequenceNumber,
-    });
-}
-
-export async function getQuestion(questionId: QuestionId): Promise<QuestionDTO | null> {
-    const question = await fetchQuestion(questionId);
+    const question = await questionRepository.findByLearningObjectAndSequenceNumber(
+        mapToLearningObjectID(questionId.learningObjectIdentifier),
+        questionId.sequenceNumber
+    );
 
     if (!question) {
-        return null;
+        throw new NotFoundException('Question with loID and sequence number not found');
     }
 
+    return question;
+}
+
+export async function getQuestion(questionId: QuestionId): Promise<QuestionDTO> {
+    const question = await fetchQuestion(questionId);
     return mapToQuestionDTO(question);
 }
 
@@ -85,53 +81,43 @@ export async function getAnswersByQuestion(questionId: QuestionId, full: boolean
     return answers.map(mapToAnswerDTOId);
 }
 
-export async function createQuestion(questionDTO: QuestionDTO): Promise<QuestionDTO | null> {
+export async function createQuestion(loId: LearningObjectIdentifier, questionData: QuestionData): Promise<QuestionDTO> {
     const questionRepository = getQuestionRepository();
+    const author = await fetchStudent(questionData.author!);
+    const content = questionData.content;
 
-    const author = mapToStudent(questionDTO.author);
+    const clazz = await getClassRepository().findById((questionData.inGroup.assignment as AssignmentDTO).within);
+    const assignment = mapToAssignment(questionData.inGroup.assignment as AssignmentDTO, clazz!);
+    const inGroup = await getGroupRepository().findByAssignmentAndGroupNumber(assignment, questionData.inGroup.groupNumber);
 
-    const loId: LearningObjectIdentifier = {
-        ...questionDTO.learningObjectIdentifier,
-        version: questionDTO.learningObjectIdentifier.version ?? 1,
-    };
-
-    const clazz = await getClassRepository().findById((questionDTO.inGroup.assignment as AssignmentDTO).class);
-    const assignment = mapToAssignment(questionDTO.inGroup.assignment as AssignmentDTO, clazz!);
-    const inGroup = await getGroupRepository().findByAssignmentAndGroupNumber(assignment, questionDTO.inGroup.groupNumber);
-
-    try {
-        await questionRepository.createQuestion({
-            loId,
-            author,
-            inGroup: inGroup!,
-            content: questionDTO.content,
-        });
-    } catch (_) {
-        return null;
-    }
-
-    return questionDTO;
-}
-
-export async function deleteQuestion(questionId: QuestionId): Promise<QuestionDTO | null> {
-    const questionRepository = getQuestionRepository();
-
-    const question = await fetchQuestion(questionId);
-
-    if (!question) {
-        return null;
-    }
-
-    const loId: LearningObjectIdentifier = {
-        ...questionId.learningObjectIdentifier,
-        version: questionId.learningObjectIdentifier.version ?? 1,
-    };
-
-    try {
-        await questionRepository.removeQuestionByLearningObjectAndSequenceNumber(loId, questionId.sequenceNumber);
-    } catch (_) {
-        return null;
-    }
+    const question = await questionRepository.createQuestion({
+        loId,
+        author,
+        inGroup: inGroup!,
+        content,
+    });
 
     return mapToQuestionDTO(question);
 }
+
+export async function deleteQuestion(questionId: QuestionId): Promise<QuestionDTO> {
+    const questionRepository = getQuestionRepository();
+    const question = await fetchQuestion(questionId); // Throws error if not found
+
+    const loId: LearningObjectIdentifier = {
+        hruid: questionId.learningObjectIdentifier.hruid,
+        language: questionId.learningObjectIdentifier.language,
+        version: questionId.learningObjectIdentifier.version || FALLBACK_VERSION_NUM,
+    };
+
+    await questionRepository.removeQuestionByLearningObjectAndSequenceNumber(loId, questionId.sequenceNumber);
+    return mapToQuestionDTO(question);
+}
+
+export async function updateQuestion(questionId: QuestionId, questionData: QuestionData): Promise<QuestionDTO> {
+    const questionRepository = getQuestionRepository();
+    const question = await fetchQuestion(questionId);
+
+    const newQuestion = await questionRepository.updateContent(question, questionData.content);
+    return mapToQuestionDTO(newQuestion);
+}
diff --git a/backend/src/services/service-helper.ts b/backend/src/services/service-helper.ts
new file mode 100644
index 00000000..641fada4
--- /dev/null
+++ b/backend/src/services/service-helper.ts
@@ -0,0 +1,20 @@
+import { EntityDTO, FromEntityType } from '@mikro-orm/core';
+import { DwengoEntityRepository } from '../data/dwengo-entity-repository';
+
+/**
+ * Utility function to perform an PUT on an object.
+ *
+ * @param object The object that needs to be changed
+ * @param data The datafields and their values that will be updated
+ * @param repo The repository on which this action needs to be performed
+ *
+ * @returns Nothing.
+ */
+export async function putObject<T extends object>(
+    object: T,
+    data: Partial<EntityDTO<FromEntityType<T>>>,
+    repo: DwengoEntityRepository<T>
+): Promise<void> {
+    repo.assign(object, data);
+    await repo.getEntityManager().flush();
+}
diff --git a/backend/src/services/students.ts b/backend/src/services/students.ts
index 960edb93..b1467886 100644
--- a/backend/src/services/students.ts
+++ b/backend/src/services/students.ts
@@ -23,6 +23,7 @@ import { GroupDTO } from '@dwengo-1/common/interfaces/group';
 import { SubmissionDTO, SubmissionDTOId } from '@dwengo-1/common/interfaces/submission';
 import { QuestionDTO, QuestionId } from '@dwengo-1/common/interfaces/question';
 import { ClassJoinRequestDTO } from '@dwengo-1/common/interfaces/class-join-request';
+import { ConflictException } from '../exceptions/conflict-exception.js';
 import { Submission } from '../entities/assignments/submission.entity';
 
 export async function getAllStudents(full: boolean): Promise<StudentDTO[] | string[]> {
@@ -137,6 +138,10 @@ export async function createClassJoinRequest(username: string, classId: string):
     const student = await fetchStudent(username); // Throws error if student not found
     const cls = await fetchClass(classId);
 
+    if (cls.students.contains(student)) {
+        throw new ConflictException('Student already in this class');
+    }
+
     const request = mapToStudentRequest(student, cls);
     await requestRepo.save(request, { preventOverwrite: true });
     return mapToStudentRequestDTO(request);
diff --git a/backend/src/services/submissions.ts b/backend/src/services/submissions.ts
index 23659d63..76141c4c 100644
--- a/backend/src/services/submissions.ts
+++ b/backend/src/services/submissions.ts
@@ -1,61 +1,56 @@
 import { getAssignmentRepository, getSubmissionRepository } from '../data/repositories.js';
 import { LearningObjectIdentifier } from '../entities/content/learning-object-identifier.js';
+import { NotFoundException } from '../exceptions/not-found-exception.js';
 import { mapToSubmission, mapToSubmissionDTO } from '../interfaces/submission.js';
 import { SubmissionDTO } from '@dwengo-1/common/interfaces/submission';
-import { Language } from '@dwengo-1/common/util/language';
-
-export async function getSubmission(
-    learningObjectHruid: string,
-    language: Language,
-    version: number,
-    submissionNumber: number
-): Promise<SubmissionDTO | null> {
-    const loId = new LearningObjectIdentifier(learningObjectHruid, language, version);
+import { fetchStudent } from './students.js';
+import { getExistingGroupFromGroupDTO } from './groups.js';
+import { Submission } from '../entities/assignments/submission.entity.js';
+import {Language} from "@dwengo-1/common/util/language";
 
+export async function fetchSubmission(loId: LearningObjectIdentifier, submissionNumber: number): Promise<Submission> {
     const submissionRepository = getSubmissionRepository();
     const submission = await submissionRepository.findSubmissionByLearningObjectAndSubmissionNumber(loId, submissionNumber);
 
     if (!submission) {
-        return null;
+        throw new NotFoundException('Could not find submission');
     }
 
-    return mapToSubmissionDTO(submission);
-}
-
-export async function createSubmission(submissionDTO: SubmissionDTO): Promise<SubmissionDTO | null> {
-    const submissionRepository = getSubmissionRepository();
-    const submission = mapToSubmission(submissionDTO);
-
-    try {
-        const newSubmission = submissionRepository.create(submission);
-        await submissionRepository.save(newSubmission);
-    } catch (_) {
-        return null;
-    }
-
-    return mapToSubmissionDTO(submission);
-}
-
-export async function deleteSubmission(
-    learningObjectHruid: string,
-    language: Language,
-    version: number,
-    submissionNumber: number
-): Promise<SubmissionDTO | null> {
-    const submissionRepository = getSubmissionRepository();
-
-    const submission = getSubmission(learningObjectHruid, language, version, submissionNumber);
-
-    if (!submission) {
-        return null;
-    }
-
-    const loId = new LearningObjectIdentifier(learningObjectHruid, language, version);
-    await submissionRepository.deleteSubmissionByLearningObjectAndSubmissionNumber(loId, submissionNumber);
-
     return submission;
 }
 
+export async function getSubmission(loId: LearningObjectIdentifier, submissionNumber: number): Promise<SubmissionDTO> {
+    const submission = await fetchSubmission(loId, submissionNumber);
+    return mapToSubmissionDTO(submission);
+}
+
+export async function getAllSubmissions(loId: LearningObjectIdentifier): Promise<SubmissionDTO[]> {
+    const submissionRepository = getSubmissionRepository();
+    const submissions = await submissionRepository.findByLearningObject(loId);
+
+    return submissions.map(mapToSubmissionDTO);
+}
+
+export async function createSubmission(submissionDTO: SubmissionDTO): Promise<SubmissionDTO> {
+    const submitter = await fetchStudent(submissionDTO.submitter.username);
+    const group = submissionDTO.group ? await getExistingGroupFromGroupDTO(submissionDTO.group) : undefined;
+
+    const submissionRepository = getSubmissionRepository();
+    const submission = mapToSubmission(submissionDTO, submitter, group);
+    await submissionRepository.save(submission);
+
+    return mapToSubmissionDTO(submission);
+}
+
+export async function deleteSubmission(loId: LearningObjectIdentifier, submissionNumber: number): Promise<SubmissionDTO> {
+    const submission = await fetchSubmission(loId, submissionNumber);
+
+    const submissionRepository = getSubmissionRepository();
+    await submissionRepository.deleteSubmissionByLearningObjectAndSubmissionNumber(loId, submissionNumber);
+
+    return mapToSubmissionDTO(submission);
+}
+
 /**
  * Returns all the submissions made by on behalf of any group the given student is in.
  */
diff --git a/backend/src/services/teachers.ts b/backend/src/services/teachers.ts
index 1b7643fb..e6596f9e 100644
--- a/backend/src/services/teachers.ts
+++ b/backend/src/services/teachers.ts
@@ -22,13 +22,14 @@ import { Question } from '../entities/questions/question.entity.js';
 import { ClassJoinRequestRepository } from '../data/classes/class-join-request-repository.js';
 import { Student } from '../entities/users/student.entity.js';
 import { NotFoundException } from '../exceptions/not-found-exception.js';
-import { getClassStudents } from './classes.js';
+import { addClassStudent, fetchClass, getClassStudentsDTO } from './classes.js';
 import { TeacherDTO } from '@dwengo-1/common/interfaces/teacher';
 import { ClassDTO } from '@dwengo-1/common/interfaces/class';
 import { StudentDTO } from '@dwengo-1/common/interfaces/student';
 import { QuestionDTO, QuestionId } from '@dwengo-1/common/interfaces/question';
 import { ClassJoinRequestDTO } from '@dwengo-1/common/interfaces/class-join-request';
 import { ClassJoinRequestStatus } from '@dwengo-1/common/util/class-join-request';
+import { ConflictException } from '../exceptions/conflict-exception.js';
 
 export async function getAllTeachers(full: boolean): Promise<TeacherDTO[] | string[]> {
     const teacherRepository: TeacherRepository = getTeacherRepository();
@@ -99,10 +100,12 @@ export async function getStudentsByTeacher(username: string, full: boolean): Pro
 
     const classIds: string[] = classes.map((cls) => cls.id);
 
-    const students: StudentDTO[] = (await Promise.all(classIds.map(async (id) => getClassStudents(id)))).flat();
+    const students: StudentDTO[] = (await Promise.all(classIds.map(async (username) => await getClassStudentsDTO(username)))).flat();
+
     if (full) {
         return students;
     }
+
     return students.map((student) => student.username);
 }
 
@@ -143,13 +146,12 @@ export async function getJoinRequestsByClass(classId: string): Promise<ClassJoin
 
 export async function updateClassJoinRequestStatus(studentUsername: string, classId: string, accepted = true): Promise<ClassJoinRequestDTO> {
     const requestRepo: ClassJoinRequestRepository = getClassJoinRequestRepository();
-    const classRepo: ClassRepository = getClassRepository();
 
     const student: Student = await fetchStudent(studentUsername);
-    const cls: Class | null = await classRepo.findById(classId);
+    const cls = await fetchClass(classId);
 
-    if (!cls) {
-        throw new NotFoundException('Class not found');
+    if (cls.students.contains(student)) {
+        throw new ConflictException('Student already in this class');
     }
 
     const request: ClassJoinRequest | null = await requestRepo.findByStudentAndClass(student, cls);
@@ -158,8 +160,14 @@ export async function updateClassJoinRequestStatus(studentUsername: string, clas
         throw new NotFoundException('Join request not found');
     }
 
-    request.status = accepted ? ClassJoinRequestStatus.Accepted : ClassJoinRequestStatus.Declined;
+    request.status = ClassJoinRequestStatus.Declined;
+
+    if (accepted) {
+        request.status = ClassJoinRequestStatus.Accepted;
+        await addClassStudent(classId, studentUsername);
+    }
 
     await requestRepo.save(request);
+
     return mapToStudentRequestDTO(request);
 }
diff --git a/backend/src/util/links.ts b/backend/src/util/links.ts
index 9ede7d12..106613a4 100644
--- a/backend/src/util/links.ts
+++ b/backend/src/util/links.ts
@@ -1,4 +1,4 @@
-import { LearningObjectIdentifier } from '@dwengo-1/common/interfaces/learning-content';
+import { LearningObjectIdentifierDTO } from '@dwengo-1/common/interfaces/learning-content';
 
 export function isValidHttpUrl(url: string): boolean {
     try {
@@ -9,7 +9,7 @@ export function isValidHttpUrl(url: string): boolean {
     }
 }
 
-export function getUrlStringForLearningObject(learningObjectId: LearningObjectIdentifier): string {
+export function getUrlStringForLearningObject(learningObjectId: LearningObjectIdentifierDTO): string {
     let url = `/learningObject/${learningObjectId.hruid}/html?language=${learningObjectId.language}`;
     if (learningObjectId.version) {
         url += `&version=${learningObjectId.version}`;
@@ -17,7 +17,7 @@ export function getUrlStringForLearningObject(learningObjectId: LearningObjectId
     return url;
 }
 
-export function getUrlStringForLearningObjectHTML(learningObjectIdentifier: LearningObjectIdentifier): string {
+export function getUrlStringForLearningObjectHTML(learningObjectIdentifier: LearningObjectIdentifierDTO): string {
     let url = `/learningObject/${learningObjectIdentifier.hruid}/html?language=${learningObjectIdentifier.language}`;
     if (learningObjectIdentifier.version) {
         url += `&version=${learningObjectIdentifier.version}`;
diff --git a/backend/tests/controllers/answers.test.ts b/backend/tests/controllers/answers.test.ts
new file mode 100644
index 00000000..2bc8ed16
--- /dev/null
+++ b/backend/tests/controllers/answers.test.ts
@@ -0,0 +1,87 @@
+import { Request, Response } from 'express';
+import { beforeAll, beforeEach, describe, expect, it, Mock, vi } from 'vitest';
+import { setupTestApp } from '../setup-tests';
+import { Language } from '@dwengo-1/common/util/language';
+import { getAllAnswersHandler, getAnswerHandler, updateAnswerHandler } from '../../src/controllers/answers';
+import { BadRequestException } from '../../src/exceptions/bad-request-exception';
+import { NotFoundException } from '../../src/exceptions/not-found-exception';
+
+describe('Questions controllers', () => {
+    let req: Partial<Request>;
+    let res: Partial<Response>;
+
+    let jsonMock: Mock;
+
+    beforeAll(async () => {
+        await setupTestApp();
+    });
+
+    beforeEach(() => {
+        jsonMock = vi.fn();
+        res = {
+            json: jsonMock,
+        };
+    });
+
+    it('Get answers list', async () => {
+        req = {
+            params: { hruid: 'id05', version: '1', seq: '2' },
+            query: { lang: Language.English, full: 'true' },
+        };
+
+        await getAllAnswersHandler(req as Request, res as Response);
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ answers: expect.anything() }));
+
+        const result = jsonMock.mock.lastCall?.[0];
+        // Console.log(result.answers);
+        expect(result.answers).to.have.length.greaterThan(1);
+    });
+
+    it('Get answer', async () => {
+        req = {
+            params: { hruid: 'id05', version: '1', seq: '2', seqAnswer: '2' },
+            query: { lang: Language.English, full: 'true' },
+        };
+
+        await getAnswerHandler(req as Request, res as Response);
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ answer: expect.anything() }));
+
+        // Const result = jsonMock.mock.lastCall?.[0];
+        // Console.log(result.answer);
+    });
+
+    it('Get answer hruid does not exist', async () => {
+        req = {
+            params: { hruid: 'id_not_exist' },
+            query: { lang: Language.English, full: 'true' },
+        };
+
+        await expect(async () => getAnswerHandler(req as Request, res as Response)).rejects.toThrow(NotFoundException);
+    });
+
+    it('Get answer no hruid given', async () => {
+        req = {
+            params: {},
+            query: { lang: Language.English, full: 'true' },
+        };
+
+        await expect(async () => getAnswerHandler(req as Request, res as Response)).rejects.toThrow(BadRequestException);
+    });
+
+    it('Update question', async () => {
+        const newContent = 'updated question';
+        req = {
+            params: { hruid: 'id05', version: '1', seq: '2', seqAnswer: '2' },
+            query: { lang: Language.English },
+            body: { content: newContent },
+        };
+
+        await updateAnswerHandler(req as Request, res as Response);
+
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ answer: expect.anything() }));
+
+        const result = jsonMock.mock.lastCall?.[0];
+        // Console.log(result.question);
+        expect(result.answer.content).to.eq(newContent);
+    });
+});
diff --git a/backend/tests/controllers/questions.test.ts b/backend/tests/controllers/questions.test.ts
new file mode 100644
index 00000000..f2612fc7
--- /dev/null
+++ b/backend/tests/controllers/questions.test.ts
@@ -0,0 +1,117 @@
+import { beforeAll, beforeEach, describe, expect, it, Mock, vi } from 'vitest';
+import { Request, Response } from 'express';
+import { setupTestApp } from '../setup-tests';
+import { getAllQuestionsHandler, getQuestionHandler, updateQuestionHandler } from '../../src/controllers/questions';
+import { Language } from '@dwengo-1/common/util/language';
+import { NotFoundException } from '../../src/exceptions/not-found-exception';
+import { BadRequestException } from '../../src/exceptions/bad-request-exception';
+
+describe('Questions controllers', () => {
+    let req: Partial<Request>;
+    let res: Partial<Response>;
+
+    let jsonMock: Mock;
+
+    beforeAll(async () => {
+        await setupTestApp();
+    });
+
+    beforeEach(() => {
+        jsonMock = vi.fn();
+        res = {
+            json: jsonMock,
+        };
+    });
+
+    it('Get question list', async () => {
+        req = {
+            params: { hruid: 'id05', version: '1' },
+            query: { lang: Language.English, full: 'true' },
+        };
+
+        await getAllQuestionsHandler(req as Request, res as Response);
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ questions: expect.anything() }));
+
+        const result = jsonMock.mock.lastCall?.[0];
+        // Console.log(result.questions);
+        expect(result.questions).to.have.length.greaterThan(1);
+    });
+
+    it('Get question', async () => {
+        req = {
+            params: { hruid: 'id05', version: '1', seq: '1' },
+            query: { lang: Language.English, full: 'true' },
+        };
+
+        await getQuestionHandler(req as Request, res as Response);
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ question: expect.anything() }));
+
+        // Const result = jsonMock.mock.lastCall?.[0];
+        // Console.log(result.question);
+    });
+
+    it('Get question with fallback sequence number and version', async () => {
+        req = {
+            params: { hruid: 'id05' },
+            query: { lang: Language.English, full: 'true' },
+        };
+
+        await getQuestionHandler(req as Request, res as Response);
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ question: expect.anything() }));
+
+        // Const result = jsonMock.mock.lastCall?.[0];
+        // Console.log(result.question);
+    });
+
+    it('Get question hruid does not exist', async () => {
+        req = {
+            params: { hruid: 'id_not_exist' },
+            query: { lang: Language.English, full: 'true' },
+        };
+
+        await expect(async () => getQuestionHandler(req as Request, res as Response)).rejects.toThrow(NotFoundException);
+    });
+
+    it('Get question no hruid given', async () => {
+        req = {
+            params: {},
+            query: { lang: Language.English, full: 'true' },
+        };
+
+        await expect(async () => getQuestionHandler(req as Request, res as Response)).rejects.toThrow(BadRequestException);
+    });
+
+    /*
+    It('Create and delete question', async() => {
+        req = {
+            params: { hruid: 'id05', version: '1', seq: '2'},
+            query: { lang: Language.English },
+        };
+
+        await deleteQuestionHandler(req as Request, res as Response);
+
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ question: expect.anything() }));
+
+        const result = jsonMock.mock.lastCall?.[0];
+        console.log(result.question);
+    });
+
+     */
+
+    it('Update question', async () => {
+        const newContent = 'updated question';
+        req = {
+            params: { hruid: 'id05', version: '1', seq: '1' },
+            query: { lang: Language.English },
+            body: { content: newContent },
+        };
+
+        await updateQuestionHandler(req as Request, res as Response);
+
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ question: expect.anything() }));
+
+        const result = jsonMock.mock.lastCall?.[0];
+        // Console.log(result.question);
+        expect(result.question.content).to.eq(newContent);
+    });
+});
diff --git a/backend/tests/controllers/students.test.ts b/backend/tests/controllers/students.test.ts
index 93f35c48..aca29de1 100644
--- a/backend/tests/controllers/students.test.ts
+++ b/backend/tests/controllers/students.test.ts
@@ -186,7 +186,7 @@ describe('Student controllers', () => {
 
     it('Get join request by student and class', async () => {
         req = {
-            params: { username: 'PinkFloyd', classId: 'id02' },
+            params: { username: 'PinkFloyd', classId: '34d484a1-295f-4e9f-bfdc-3e7a23d86a89' },
         };
 
         await getStudentRequestHandler(req as Request, res as Response);
@@ -198,29 +198,18 @@ describe('Student controllers', () => {
         );
     });
 
-    it('Create join request', async () => {
+    it('Create and delete join request', async () => {
         req = {
-            params: { username: 'Noordkaap' },
-            body: { classId: 'id02' },
+            params: { username: 'TheDoors' },
+            body: { classId: '34d484a1-295f-4e9f-bfdc-3e7a23d86a89' },
         };
 
         await createStudentRequestHandler(req as Request, res as Response);
 
         expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ request: expect.anything() }));
-    });
 
-    it('Create join request duplicate', async () => {
         req = {
-            params: { username: 'Tool' },
-            body: { classId: 'id02' },
-        };
-
-        await expect(async () => createStudentRequestHandler(req as Request, res as Response)).rejects.toThrow(ConflictException);
-    });
-
-    it('Delete join request', async () => {
-        req = {
-            params: { username: 'Noordkaap', classId: 'id02' },
+            params: { username: 'TheDoors', classId: '34d484a1-295f-4e9f-bfdc-3e7a23d86a89' },
         };
 
         await deleteClassJoinRequestHandler(req as Request, res as Response);
@@ -229,4 +218,22 @@ describe('Student controllers', () => {
 
         await expect(async () => deleteClassJoinRequestHandler(req as Request, res as Response)).rejects.toThrow(NotFoundException);
     });
+
+    it('Create join request student already in class error', async () => {
+        req = {
+            params: { username: 'Noordkaap' },
+            body: { classId: '34d484a1-295f-4e9f-bfdc-3e7a23d86a89' },
+        };
+
+        await expect(async () => createStudentRequestHandler(req as Request, res as Response)).rejects.toThrow(ConflictException);
+    });
+
+    it('Create join request duplicate', async () => {
+        req = {
+            params: { username: 'Tool' },
+            body: { classId: '34d484a1-295f-4e9f-bfdc-3e7a23d86a89' },
+        };
+
+        await expect(async () => createStudentRequestHandler(req as Request, res as Response)).rejects.toThrow(ConflictException);
+    });
 });
diff --git a/backend/tests/controllers/teachers.test.ts b/backend/tests/controllers/teachers.test.ts
index bee23987..a73a79a5 100644
--- a/backend/tests/controllers/teachers.test.ts
+++ b/backend/tests/controllers/teachers.test.ts
@@ -16,6 +16,7 @@ import { BadRequestException } from '../../src/exceptions/bad-request-exception.
 import { EntityAlreadyExistsException } from '../../src/exceptions/entity-already-exists-exception.js';
 import { getStudentRequestsHandler } from '../../src/controllers/students.js';
 import { TeacherDTO } from '@dwengo-1/common/interfaces/teacher';
+import { getClassHandler } from '../../src/controllers/classes';
 
 describe('Teacher controllers', () => {
     let req: Partial<Request>;
@@ -104,9 +105,9 @@ describe('Teacher controllers', () => {
         const result = jsonMock.mock.lastCall?.[0];
 
         const teacherUsernames = result.teachers.map((s: TeacherDTO) => s.username);
-        expect(teacherUsernames).toContain('FooFighters');
+        expect(teacherUsernames).toContain('testleerkracht1');
 
-        expect(result.teachers).toHaveLength(4);
+        expect(result.teachers).toHaveLength(5);
     });
 
     it('Deleting non-existent student', async () => {
@@ -117,7 +118,7 @@ describe('Teacher controllers', () => {
 
     it('Get teacher classes', async () => {
         req = {
-            params: { username: 'FooFighters' },
+            params: { username: 'testleerkracht1' },
             query: { full: 'true' },
         };
 
@@ -132,7 +133,7 @@ describe('Teacher controllers', () => {
 
     it('Get teacher students', async () => {
         req = {
-            params: { username: 'FooFighters' },
+            params: { username: 'testleerkracht1' },
             query: { full: 'true' },
         };
 
@@ -168,8 +169,7 @@ describe('Teacher controllers', () => {
 
     it('Get join requests by class', async () => {
         req = {
-            query: { username: 'LimpBizkit' },
-            params: { classId: 'id02' },
+            params: { classId: '34d484a1-295f-4e9f-bfdc-3e7a23d86a89' },
         };
 
         await getStudentJoinRequestHandler(req as Request, res as Response);
@@ -183,8 +183,7 @@ describe('Teacher controllers', () => {
 
     it('Update join request status', async () => {
         req = {
-            query: { username: 'LimpBizkit', studentUsername: 'PinkFloyd' },
-            params: { classId: 'id02' },
+            params: { classId: '34d484a1-295f-4e9f-bfdc-3e7a23d86a89', studentUsername: 'PinkFloyd' },
             body: { accepted: 'true' },
         };
 
@@ -200,5 +199,13 @@ describe('Teacher controllers', () => {
 
         const status: boolean = jsonMock.mock.lastCall?.[0].requests[0].status;
         expect(status).toBeTruthy();
+
+        req = {
+            params: { id: '34d484a1-295f-4e9f-bfdc-3e7a23d86a89' },
+        };
+
+        await getClassHandler(req as Request, res as Response);
+        const students: string[] = jsonMock.mock.lastCall?.[0].class.students;
+        expect(students).contains('PinkFloyd');
     });
 });
diff --git a/backend/tests/data/assignments/assignments.test.ts b/backend/tests/data/assignments/assignments.test.ts
index 2bad08f2..206ab4fd 100644
--- a/backend/tests/data/assignments/assignments.test.ts
+++ b/backend/tests/data/assignments/assignments.test.ts
@@ -15,7 +15,7 @@ describe('AssignmentRepository', () => {
     });
 
     it('should return the requested assignment', async () => {
-        const class_ = await classRepository.findById('id02');
+        const class_ = await classRepository.findById('34d484a1-295f-4e9f-bfdc-3e7a23d86a89');
         const assignment = await assignmentRepository.findByClassAndId(class_!, 2);
 
         expect(assignment).toBeTruthy();
@@ -23,7 +23,7 @@ describe('AssignmentRepository', () => {
     });
 
     it('should return all assignments for a class', async () => {
-        const class_ = await classRepository.findById('id02');
+        const class_ = await classRepository.findById('34d484a1-295f-4e9f-bfdc-3e7a23d86a89');
         const assignments = await assignmentRepository.findAllAssignmentsInClass(class_!);
 
         expect(assignments).toBeTruthy();
diff --git a/backend/tests/data/assignments/groups.test.ts b/backend/tests/data/assignments/groups.test.ts
index 96684d68..f7fb3046 100644
--- a/backend/tests/data/assignments/groups.test.ts
+++ b/backend/tests/data/assignments/groups.test.ts
@@ -18,7 +18,7 @@ describe('GroupRepository', () => {
     });
 
     it('should return the requested group', async () => {
-        const class_ = await classRepository.findById('id01');
+        const class_ = await classRepository.findById('8764b861-90a6-42e5-9732-c0d9eb2f55f9');
         const assignment = await assignmentRepository.findByClassAndId(class_!, 1);
 
         const group = await groupRepository.findByAssignmentAndGroupNumber(assignment!, 1);
@@ -27,7 +27,7 @@ describe('GroupRepository', () => {
     });
 
     it('should return all groups for assignment', async () => {
-        const class_ = await classRepository.findById('id01');
+        const class_ = await classRepository.findById('8764b861-90a6-42e5-9732-c0d9eb2f55f9');
         const assignment = await assignmentRepository.findByClassAndId(class_!, 1);
 
         const groups = await groupRepository.findAllGroupsForAssignment(assignment!);
@@ -37,7 +37,7 @@ describe('GroupRepository', () => {
     });
 
     it('should not find removed group', async () => {
-        const class_ = await classRepository.findById('id02');
+        const class_ = await classRepository.findById('34d484a1-295f-4e9f-bfdc-3e7a23d86a89');
         const assignment = await assignmentRepository.findByClassAndId(class_!, 2);
 
         await groupRepository.deleteByAssignmentAndGroupNumber(assignment!, 1);
diff --git a/backend/tests/data/assignments/submissions.test.ts b/backend/tests/data/assignments/submissions.test.ts
index acc82384..47e1c414 100644
--- a/backend/tests/data/assignments/submissions.test.ts
+++ b/backend/tests/data/assignments/submissions.test.ts
@@ -53,7 +53,7 @@ describe('SubmissionRepository', () => {
 
     it('should find the most recent submission for a group', async () => {
         const id = new LearningObjectIdentifier('id03', Language.English, 1);
-        const class_ = await classRepository.findById('id01');
+        const class_ = await classRepository.findById('8764b861-90a6-42e5-9732-c0d9eb2f55f9');
         const assignment = await assignmentRepository.findByClassAndId(class_!, 1);
         const group = await groupRepository.findByAssignmentAndGroupNumber(assignment!, 1);
         const submission = await submissionRepository.findMostRecentSubmissionForGroup(id, group!);
diff --git a/backend/tests/data/classes/class-join-request.test.ts b/backend/tests/data/classes/class-join-request.test.ts
index cd53bf05..afb83766 100644
--- a/backend/tests/data/classes/class-join-request.test.ts
+++ b/backend/tests/data/classes/class-join-request.test.ts
@@ -26,7 +26,7 @@ describe('ClassJoinRequestRepository', () => {
     });
 
     it('should list all requests to a single class', async () => {
-        const class_ = await cassRepository.findById('id02');
+        const class_ = await cassRepository.findById('34d484a1-295f-4e9f-bfdc-3e7a23d86a89');
         const requests = await classJoinRequestRepository.findAllOpenRequestsTo(class_!);
 
         expect(requests).toBeTruthy();
@@ -35,7 +35,7 @@ describe('ClassJoinRequestRepository', () => {
 
     it('should not find a removed request', async () => {
         const student = await studentRepository.findByUsername('SmashingPumpkins');
-        const class_ = await cassRepository.findById('id03');
+        const class_ = await cassRepository.findById('80dcc3e0-1811-4091-9361-42c0eee91cfa');
         await classJoinRequestRepository.deleteBy(student!, class_!);
 
         const request = await classJoinRequestRepository.findAllRequestsBy(student!);
diff --git a/backend/tests/data/classes/classes.test.ts b/backend/tests/data/classes/classes.test.ts
index 22306ba6..f87f83ed 100644
--- a/backend/tests/data/classes/classes.test.ts
+++ b/backend/tests/data/classes/classes.test.ts
@@ -18,16 +18,16 @@ describe('ClassRepository', () => {
     });
 
     it('should return requested class', async () => {
-        const classVar = await classRepository.findById('id01');
+        const classVar = await classRepository.findById('8764b861-90a6-42e5-9732-c0d9eb2f55f9');
 
         expect(classVar).toBeTruthy();
         expect(classVar?.displayName).toBe('class01');
     });
 
     it('class should be gone after deletion', async () => {
-        await classRepository.deleteById('id04');
+        await classRepository.deleteById('33d03536-83b8-4880-9982-9bbf2f908ddf');
 
-        const classVar = await classRepository.findById('id04');
+        const classVar = await classRepository.findById('33d03536-83b8-4880-9982-9bbf2f908ddf');
 
         expect(classVar).toBeNull();
     });
diff --git a/backend/tests/data/classes/teacher-invitation.test.ts b/backend/tests/data/classes/teacher-invitation.test.ts
index dd03634a..f8afa36d 100644
--- a/backend/tests/data/classes/teacher-invitation.test.ts
+++ b/backend/tests/data/classes/teacher-invitation.test.ts
@@ -34,7 +34,7 @@ describe('ClassRepository', () => {
     });
 
     it('should return all invitations for a class', async () => {
-        const class_ = await classRepository.findById('id02');
+        const class_ = await classRepository.findById('34d484a1-295f-4e9f-bfdc-3e7a23d86a89');
         const invitations = await teacherInvitationRepository.findAllInvitationsForClass(class_!);
 
         expect(invitations).toBeTruthy();
@@ -42,7 +42,7 @@ describe('ClassRepository', () => {
     });
 
     it('should not find a removed invitation', async () => {
-        const class_ = await classRepository.findById('id01');
+        const class_ = await classRepository.findById('8764b861-90a6-42e5-9732-c0d9eb2f55f9');
         const sender = await teacherRepository.findByUsername('FooFighters');
         const receiver = await teacherRepository.findByUsername('LimpBizkit');
         await teacherInvitationRepository.deleteBy(class_!, sender!, receiver!);
diff --git a/backend/tests/services/learning-objects/learning-object-service.test.ts b/backend/tests/services/learning-objects/learning-object-service.test.ts
index a0fea849..3ea4143d 100644
--- a/backend/tests/services/learning-objects/learning-object-service.test.ts
+++ b/backend/tests/services/learning-objects/learning-object-service.test.ts
@@ -7,11 +7,11 @@ import learningObjectService from '../../../src/services/learning-objects/learni
 import { envVars, getEnvVar } from '../../../src/util/envVars';
 import { LearningPath } from '../../../src/entities/content/learning-path.entity';
 import learningPathExample from '../../test-assets/learning-paths/pn-werking-example';
-import { LearningObjectIdentifier, LearningPathIdentifier } from '@dwengo-1/common/interfaces/learning-content';
+import { LearningObjectIdentifierDTO, LearningPathIdentifier } from '@dwengo-1/common/interfaces/learning-content';
 import { Language } from '@dwengo-1/common/util/language';
 
 const EXPECTED_DWENGO_LEARNING_OBJECT_TITLE = 'Werken met notebooks';
-const DWENGO_TEST_LEARNING_OBJECT_ID: LearningObjectIdentifier = {
+const DWENGO_TEST_LEARNING_OBJECT_ID: LearningObjectIdentifierDTO = {
     hruid: 'pn_werkingnotebooks',
     language: Language.Dutch,
     version: 3,
diff --git a/backend/tests/test_assets/classes/classes.testdata.ts b/backend/tests/test_assets/classes/classes.testdata.ts
index e4372015..0f223ec4 100644
--- a/backend/tests/test_assets/classes/classes.testdata.ts
+++ b/backend/tests/test_assets/classes/classes.testdata.ts
@@ -4,11 +4,11 @@ import { Student } from '../../../src/entities/users/student.entity';
 import { Teacher } from '../../../src/entities/users/teacher.entity';
 
 export function makeTestClasses(em: EntityManager, students: Student[], teachers: Teacher[]): Class[] {
-    const studentsClass01 = students.slice(0, 7);
-    const teacherClass01: Teacher[] = teachers.slice(0, 1);
+    const studentsClass01 = students.slice(0, 8);
+    const teacherClass01: Teacher[] = teachers.slice(4, 5);
 
     const class01 = em.create(Class, {
-        classId: 'id01',
+        classId: '8764b861-90a6-42e5-9732-c0d9eb2f55f9',
         displayName: 'class01',
         teachers: teacherClass01,
         students: studentsClass01,
@@ -18,7 +18,7 @@ export function makeTestClasses(em: EntityManager, students: Student[], teachers
     const teacherClass02: Teacher[] = teachers.slice(1, 2);
 
     const class02 = em.create(Class, {
-        classId: 'id02',
+        classId: '34d484a1-295f-4e9f-bfdc-3e7a23d86a89',
         displayName: 'class02',
         teachers: teacherClass02,
         students: studentsClass02,
@@ -28,7 +28,7 @@ export function makeTestClasses(em: EntityManager, students: Student[], teachers
     const teacherClass03: Teacher[] = teachers.slice(2, 3);
 
     const class03 = em.create(Class, {
-        classId: 'id03',
+        classId: '80dcc3e0-1811-4091-9361-42c0eee91cfa',
         displayName: 'class03',
         teachers: teacherClass03,
         students: studentsClass03,
@@ -38,7 +38,7 @@ export function makeTestClasses(em: EntityManager, students: Student[], teachers
     const teacherClass04: Teacher[] = teachers.slice(2, 3);
 
     const class04 = em.create(Class, {
-        classId: 'id04',
+        classId: '33d03536-83b8-4880-9982-9bbf2f908ddf',
         displayName: 'class04',
         teachers: teacherClass04,
         students: studentsClass04,
diff --git a/backend/tests/test_assets/users/students.testdata.ts b/backend/tests/test_assets/users/students.testdata.ts
index 5cd75787..7a1fe191 100644
--- a/backend/tests/test_assets/users/students.testdata.ts
+++ b/backend/tests/test_assets/users/students.testdata.ts
@@ -11,6 +11,8 @@ export const TEST_STUDENTS = [
     { username: 'TheDoors', firstName: 'Jim', lastName: 'Morisson' },
     // ⚠️ Deze mag niet gebruikt worden in elke test!
     { username: 'Nirvana', firstName: 'Kurt', lastName: 'Cobain' },
+    // Makes sure when logged in as leerling1, there exists a corresponding user
+    { username: 'testleerling1', firstName: 'Gerald', lastName: 'Schmittinger' },
 ];
 
 // 🏗️ Functie die ORM entities maakt uit de data array
diff --git a/backend/tests/test_assets/users/teachers.testdata.ts b/backend/tests/test_assets/users/teachers.testdata.ts
index 8e791bb1..db726dcf 100644
--- a/backend/tests/test_assets/users/teachers.testdata.ts
+++ b/backend/tests/test_assets/users/teachers.testdata.ts
@@ -27,5 +27,12 @@ export function makeTestTeachers(em: EntityManager): Teacher[] {
         lastName: 'Cappelle',
     });
 
-    return [teacher01, teacher02, teacher03, teacher04];
+    // Makes sure when logged in as testleerkracht1, there exists a corresponding user
+    const teacher05 = em.create(Teacher, {
+        username: 'testleerkracht1',
+        firstName: 'Bob',
+        lastName: 'Dylan',
+    });
+
+    return [teacher01, teacher02, teacher03, teacher04, teacher05];
 }
diff --git a/backend/tool/seed.ts b/backend/tool/seed.ts
new file mode 100644
index 00000000..33344234
--- /dev/null
+++ b/backend/tool/seed.ts
@@ -0,0 +1,72 @@
+import { forkEntityManager, initORM } from '../src/orm.js';
+import dotenv from 'dotenv';
+import { makeTestAssignemnts } from '../tests/test_assets/assignments/assignments.testdata.js';
+import { makeTestGroups } from '../tests/test_assets/assignments/groups.testdata.js';
+import { makeTestSubmissions } from '../tests/test_assets/assignments/submission.testdata.js';
+import { makeTestClassJoinRequests } from '../tests/test_assets/classes/class-join-requests.testdata.js';
+import { makeTestClasses } from '../tests/test_assets/classes/classes.testdata.js';
+import { makeTestTeacherInvitations } from '../tests/test_assets/classes/teacher-invitations.testdata.js';
+import { makeTestAttachments } from '../tests/test_assets/content/attachments.testdata.js';
+import { makeTestLearningObjects } from '../tests/test_assets/content/learning-objects.testdata.js';
+import { makeTestLearningPaths } from '../tests/test_assets/content/learning-paths.testdata.js';
+import { makeTestAnswers } from '../tests/test_assets/questions/answers.testdata.js';
+import { makeTestQuestions } from '../tests/test_assets/questions/questions.testdata.js';
+import { makeTestStudents } from '../tests/test_assets/users/students.testdata.js';
+import { makeTestTeachers } from '../tests/test_assets/users/teachers.testdata.js';
+import { getLogger, Logger } from '../src/logging/initalize.js';
+
+const logger: Logger = getLogger();
+
+export async function seedDatabase(): Promise<void> {
+    dotenv.config({ path: '.env.development.local' });
+    const orm = await initORM();
+    await orm.schema.clearDatabase();
+
+    const em = forkEntityManager();
+
+    logger.info('seeding database...');
+
+    const students = makeTestStudents(em);
+    const teachers = makeTestTeachers(em);
+    const learningObjects = makeTestLearningObjects(em);
+    const learningPaths = makeTestLearningPaths(em);
+    const classes = makeTestClasses(em, students, teachers);
+    const assignments = makeTestAssignemnts(em, classes);
+    const groups = makeTestGroups(em, students, assignments);
+
+    assignments[0].groups = groups.slice(0, 3);
+    assignments[1].groups = groups.slice(3, 4);
+
+    const teacherInvitations = makeTestTeacherInvitations(em, teachers, classes);
+    const classJoinRequests = makeTestClassJoinRequests(em, students, classes);
+    const attachments = makeTestAttachments(em, learningObjects);
+
+    learningObjects[1].attachments = attachments;
+
+    const questions = makeTestQuestions(em, students);
+    const answers = makeTestAnswers(em, teachers, questions);
+    const submissions = makeTestSubmissions(em, students, groups);
+
+    // Persist all entities
+    await em.persistAndFlush([
+        ...students,
+        ...teachers,
+        ...learningObjects,
+        ...learningPaths,
+        ...classes,
+        ...assignments,
+        ...groups,
+        ...teacherInvitations,
+        ...classJoinRequests,
+        ...attachments,
+        ...questions,
+        ...answers,
+        ...submissions,
+    ]);
+
+    logger.info('Development database seeded successfully!');
+
+    await orm.close();
+}
+
+seedDatabase().catch(logger.error);
diff --git a/common/src/interfaces/answer.ts b/common/src/interfaces/answer.ts
index e9280f8a..8510ac7b 100644
--- a/common/src/interfaces/answer.ts
+++ b/common/src/interfaces/answer.ts
@@ -1,14 +1,19 @@
-import { UserDTO } from './user';
 import { QuestionDTO, QuestionId } from './question';
+import { TeacherDTO } from './teacher';
 
 export interface AnswerDTO {
-    author: UserDTO;
+    author: TeacherDTO;
     toQuestion: QuestionDTO;
     sequenceNumber: number;
     timestamp: string;
     content: string;
 }
 
+export interface AnswerData {
+    author: string;
+    content: string;
+}
+
 export interface AnswerId {
     author: string;
     toQuestion: QuestionId;
diff --git a/common/src/interfaces/assignment.ts b/common/src/interfaces/assignment.ts
index 8ad1649b..5cb8feff 100644
--- a/common/src/interfaces/assignment.ts
+++ b/common/src/interfaces/assignment.ts
@@ -2,7 +2,7 @@ import { GroupDTO } from './group';
 
 export interface AssignmentDTO {
     id: number;
-    class: string; // Id of class 'within'
+    within: string;
     title: string;
     description: string;
     learningPath: string;
diff --git a/common/src/interfaces/class.ts b/common/src/interfaces/class.ts
index c35c2dfc..d71e15e6 100644
--- a/common/src/interfaces/class.ts
+++ b/common/src/interfaces/class.ts
@@ -3,5 +3,4 @@ export interface ClassDTO {
     displayName: string;
     teachers: string[];
     students: string[];
-    joinRequests: string[];
 }
diff --git a/common/src/interfaces/group.ts b/common/src/interfaces/group.ts
index 16e22780..6baa79a5 100644
--- a/common/src/interfaces/group.ts
+++ b/common/src/interfaces/group.ts
@@ -1,7 +1,9 @@
 import { AssignmentDTO } from './assignment';
+import { ClassDTO } from './class';
 import { StudentDTO } from './student';
 
 export interface GroupDTO {
+    class: string | ClassDTO;
     assignment: number | AssignmentDTO;
     groupNumber: number;
     members?: string[] | StudentDTO[];
diff --git a/common/src/interfaces/learning-content.ts b/common/src/interfaces/learning-content.ts
index 02e49648..435e7001 100644
--- a/common/src/interfaces/learning-content.ts
+++ b/common/src/interfaces/learning-content.ts
@@ -11,7 +11,7 @@ export interface Transition {
     };
 }
 
-export interface LearningObjectIdentifier {
+export interface LearningObjectIdentifierDTO {
     hruid: string;
     language: Language;
     version?: number;
diff --git a/common/src/interfaces/question.ts b/common/src/interfaces/question.ts
index bd689c34..f5eceffd 100644
--- a/common/src/interfaces/question.ts
+++ b/common/src/interfaces/question.ts
@@ -1,17 +1,17 @@
-import { LearningObjectIdentifier } from './learning-content';
+import { LearningObjectIdentifierDTO } from './learning-content';
 import { StudentDTO } from './student';
 import { GroupDTO } from './group';
 
 export interface QuestionDTO {
-    learningObjectIdentifier: LearningObjectIdentifier;
+    learningObjectIdentifier: LearningObjectIdentifierDTO;
     sequenceNumber?: number;
     author: StudentDTO;
     inGroup: GroupDTO;
-    timestamp?: string;
+    timestamp: string;
     content: string;
 }
 
 export interface QuestionId {
-    learningObjectIdentifier: LearningObjectIdentifier;
+    learningObjectIdentifier: LearningObjectIdentifierDTO;
     sequenceNumber: number;
 }
diff --git a/common/src/interfaces/submission.ts b/common/src/interfaces/submission.ts
index f63660b1..7643f0e6 100644
--- a/common/src/interfaces/submission.ts
+++ b/common/src/interfaces/submission.ts
@@ -1,10 +1,10 @@
 import { GroupDTO } from './group';
-import { LearningObjectIdentifier } from './learning-content';
+import { LearningObjectIdentifierDTO } from './learning-content';
 import { StudentDTO } from './student';
 import { Language } from '../util/language';
 
 export interface SubmissionDTO {
-    learningObjectIdentifier: LearningObjectIdentifier;
+    learningObjectIdentifier: LearningObjectIdentifierDTO;
 
     submissionNumber?: number;
     submitter: StudentDTO;
diff --git a/compose.production.yml b/compose.production.yml
index e6f140d4..7c8ad946 100644
--- a/compose.production.yml
+++ b/compose.production.yml
@@ -24,7 +24,7 @@ services:
         restart: unless-stopped
         volumes:
             # TODO Replace with environment keys
-            - ./backend/.env:/app/.env
+            - ./backend/.env:/app/dwengo/backend/.env
         depends_on:
             - db
             - logging
diff --git a/compose.staging.yml b/compose.staging.yml
index 16814b77..253ab7d5 100644
--- a/compose.staging.yml
+++ b/compose.staging.yml
@@ -24,7 +24,7 @@ services:
             - '3000:3000/tcp'
         restart: unless-stopped
         volumes:
-            - ./backend/.env.staging:/app/.env
+            - ./backend/.env.staging:/app/dwengo/backend/.env
         depends_on:
             - db
             - logging
diff --git a/frontend/src/controllers/answers.ts b/frontend/src/controllers/answers.ts
new file mode 100644
index 00000000..04235e77
--- /dev/null
+++ b/frontend/src/controllers/answers.ts
@@ -0,0 +1,39 @@
+import type { AnswerData, AnswerDTO, AnswerId } from "@dwengo-1/common/interfaces/answer";
+import { BaseController } from "@/controllers/base-controller.ts";
+import type { QuestionId } from "@dwengo-1/common/interfaces/question";
+
+export interface AnswersResponse {
+    answers: AnswerDTO[] | AnswerId[];
+}
+
+export interface AnswerResponse {
+    answer: AnswerDTO;
+}
+
+export class AnswerController extends BaseController {
+    constructor(questionId: QuestionId) {
+        this.loId = questionId.learningObjectIdentifier;
+        this.sequenceNumber = questionId.sequenceNumber;
+        super(`learningObject/${loId.hruid}/:${loId.version}/questions/${this.sequenceNumber}/answers`);
+    }
+
+    async getAll(full = true): Promise<AnswersResponse> {
+        return this.get<AnswersResponse>("/", { lang: this.loId.lang, full });
+    }
+
+    async getBy(seq: number): Promise<AnswerResponse> {
+        return this.get<AnswerResponse>(`/${seq}`, { lang: this.loId.lang });
+    }
+
+    async create(answerData: AnswerData): Promise<AnswerResponse> {
+        return this.post<AnswerResponse>("/", answerData, { lang: this.loId.lang });
+    }
+
+    async remove(seq: number): Promise<AnswerResponse> {
+        return this.delete<AnswerResponse>(`/${seq}`, { lang: this.loId.lang });
+    }
+
+    async update(seq: number, answerData: AnswerData): Promise<AnswerResponse> {
+        return this.put<AnswerResponse>(`/${seq}`, answerData, { lang: this.loId.lang });
+    }
+}
diff --git a/frontend/src/controllers/assignments.ts b/frontend/src/controllers/assignments.ts
index 5fd5090a..a66f8e84 100644
--- a/frontend/src/controllers/assignments.ts
+++ b/frontend/src/controllers/assignments.ts
@@ -1,5 +1,51 @@
-import type { AssignmentDTO } from "@dwengo-1/interfaces/assignment";
+import { BaseController } from "./base-controller";
+import type { AssignmentDTO } from "@dwengo-1/common/interfaces/assignment";
+import type { SubmissionsResponse } from "./submissions";
+import type { QuestionsResponse } from "./questions";
+import type { GroupsResponse } from "./groups";
 
 export interface AssignmentsResponse {
-    assignments: AssignmentDTO[];
-} // TODO ID
+    assignments: AssignmentDTO[] | string[];
+}
+
+export interface AssignmentResponse {
+    assignment: AssignmentDTO;
+}
+
+export class AssignmentController extends BaseController {
+    constructor(classid: string) {
+        super(`class/${classid}/assignments`);
+    }
+
+    async getAll(full = true): Promise<AssignmentsResponse> {
+        return this.get<AssignmentsResponse>(`/`, { full });
+    }
+
+    async getByNumber(num: number): Promise<AssignmentResponse> {
+        return this.get<AssignmentResponse>(`/${num}`);
+    }
+
+    async createAssignment(data: AssignmentDTO): Promise<AssignmentResponse> {
+        return this.post<AssignmentResponse>(`/`, data);
+    }
+
+    async deleteAssignment(num: number): Promise<AssignmentResponse> {
+        return this.delete<AssignmentResponse>(`/${num}`);
+    }
+
+    async updateAssignment(num: number, data: Partial<AssignmentDTO>): Promise<AssignmentResponse> {
+        return this.put<AssignmentResponse>(`/${num}`, data);
+    }
+
+    async getSubmissions(assignmentNumber: number, full = true): Promise<SubmissionsResponse> {
+        return this.get<SubmissionsResponse>(`/${assignmentNumber}/submissions`, { full });
+    }
+
+    async getQuestions(assignmentNumber: number, full = true): Promise<QuestionsResponse> {
+        return this.get<QuestionsResponse>(`/${assignmentNumber}/questions`, { full });
+    }
+
+    async getGroups(assignmentNumber: number, full = true): Promise<GroupsResponse> {
+        return this.get<GroupsResponse>(`/${assignmentNumber}/groups`, { full });
+    }
+}
diff --git a/frontend/src/controllers/base-controller.ts b/frontend/src/controllers/base-controller.ts
index 72d71819..3d22e099 100644
--- a/frontend/src/controllers/base-controller.ts
+++ b/frontend/src/controllers/base-controller.ts
@@ -10,7 +10,7 @@ export abstract class BaseController {
     }
 
     private static assertSuccessResponse(response: AxiosResponse<unknown, unknown>): void {
-        if (response.status / 100 !== 2) {
+        if (response.status < 200 || response.status >= 300) {
             throw new HttpErrorResponseException(response);
         }
     }
@@ -21,20 +21,20 @@ export abstract class BaseController {
         return response.data;
     }
 
-    protected async post<T>(path: string, body: unknown): Promise<T> {
-        const response = await apiClient.post<T>(this.absolutePathFor(path), body);
+    protected async post<T>(path: string, body: unknown, queryParams?: QueryParams): Promise<T> {
+        const response = await apiClient.post<T>(this.absolutePathFor(path), body, { params: queryParams });
         BaseController.assertSuccessResponse(response);
         return response.data;
     }
 
-    protected async delete<T>(path: string): Promise<T> {
-        const response = await apiClient.delete<T>(this.absolutePathFor(path));
+    protected async delete<T>(path: string, queryParams?: QueryParams): Promise<T> {
+        const response = await apiClient.delete<T>(this.absolutePathFor(path), { params: queryParams });
         BaseController.assertSuccessResponse(response);
         return response.data;
     }
 
-    protected async put<T>(path: string, body: unknown): Promise<T> {
-        const response = await apiClient.put<T>(this.absolutePathFor(path), body);
+    protected async put<T>(path: string, body: unknown, queryParams?: QueryParams): Promise<T> {
+        const response = await apiClient.put<T>(this.absolutePathFor(path), body, { params: queryParams });
         BaseController.assertSuccessResponse(response);
         return response.data;
     }
diff --git a/frontend/src/controllers/classes.ts b/frontend/src/controllers/classes.ts
index d2d95ed5..03e3f560 100644
--- a/frontend/src/controllers/classes.ts
+++ b/frontend/src/controllers/classes.ts
@@ -1,5 +1,80 @@
-import type { ClassDTO } from "@dwengo-1/interfaces/class";
+import { BaseController } from "./base-controller";
+import type { ClassDTO } from "@dwengo-1/common/interfaces/class";
+import type { StudentsResponse } from "./students";
+import type { AssignmentsResponse } from "./assignments";
+import type { TeacherInvitationDTO } from "@dwengo-1/common/interfaces/teacher-invitation";
+import type { TeachersResponse } from "@/controllers/teachers.ts";
 
 export interface ClassesResponse {
     classes: ClassDTO[] | string[];
 }
+
+export interface ClassResponse {
+    class: ClassDTO;
+}
+
+export interface TeacherInvitationsResponse {
+    invites: TeacherInvitationDTO[];
+}
+
+export interface TeacherInvitationResponse {
+    invite: TeacherInvitationDTO;
+}
+
+export class ClassController extends BaseController {
+    constructor() {
+        super("class");
+    }
+
+    async getAll(full = true): Promise<ClassesResponse> {
+        return this.get<ClassesResponse>(`/`, { full });
+    }
+
+    async getById(id: string): Promise<ClassResponse> {
+        return this.get<ClassResponse>(`/${id}`);
+    }
+
+    async createClass(data: ClassDTO): Promise<ClassResponse> {
+        return this.post<ClassResponse>(`/`, data);
+    }
+
+    async deleteClass(id: string): Promise<ClassResponse> {
+        return this.delete<ClassResponse>(`/${id}`);
+    }
+
+    async updateClass(id: string, data: Partial<ClassDTO>): Promise<ClassResponse> {
+        return this.put<ClassResponse>(`/${id}`, data);
+    }
+
+    async getStudents(id: string, full = true): Promise<StudentsResponse> {
+        return this.get<StudentsResponse>(`/${id}/students`, { full });
+    }
+
+    async addStudent(id: string, username: string): Promise<ClassResponse> {
+        return this.post<ClassResponse>(`/${id}/students`, { username });
+    }
+
+    async deleteStudent(id: string, username: string): Promise<ClassResponse> {
+        return this.delete<ClassResponse>(`/${id}/students/${username}`);
+    }
+
+    async getTeachers(id: string, full = true): Promise<TeachersResponse> {
+        return this.get<TeachersResponse>(`/${id}/teachers`, { full });
+    }
+
+    async addTeacher(id: string, username: string): Promise<ClassResponse> {
+        return this.post<ClassResponse>(`/${id}/teachers`, { username });
+    }
+
+    async deleteTeacher(id: string, username: string): Promise<ClassResponse> {
+        return this.delete<ClassResponse>(`/${id}/teachers/${username}`);
+    }
+
+    async getTeacherInvitations(id: string, full = true): Promise<TeacherInvitationsResponse> {
+        return this.get<TeacherInvitationsResponse>(`/${id}/teacher-invitations`, { full });
+    }
+
+    async getAssignments(id: string, full = true): Promise<AssignmentsResponse> {
+        return this.get<AssignmentsResponse>(`/${id}/assignments`, { full });
+    }
+}
diff --git a/frontend/src/controllers/controllers.ts b/frontend/src/controllers/controllers.ts
index 39392a7d..d8dbc9e2 100644
--- a/frontend/src/controllers/controllers.ts
+++ b/frontend/src/controllers/controllers.ts
@@ -1,6 +1,7 @@
 import { ThemeController } from "@/controllers/themes.ts";
 import { LearningObjectController } from "@/controllers/learning-objects.ts";
 import { LearningPathController } from "@/controllers/learning-paths.ts";
+import { ClassController } from "@/controllers/classes.ts";
 
 export function controllerGetter<T>(factory: new () => T): () => T {
     let instance: T | undefined;
@@ -16,3 +17,4 @@ export function controllerGetter<T>(factory: new () => T): () => T {
 export const getThemeController = controllerGetter(ThemeController);
 export const getLearningObjectController = controllerGetter(LearningObjectController);
 export const getLearningPathController = controllerGetter(LearningPathController);
+export const getClassController = controllerGetter(ClassController);
diff --git a/frontend/src/controllers/groups.ts b/frontend/src/controllers/groups.ts
index d6738e04..de6592b5 100644
--- a/frontend/src/controllers/groups.ts
+++ b/frontend/src/controllers/groups.ts
@@ -1,5 +1,46 @@
-import type { GroupDTO } from "@dwengo-1/interfaces/group";
+import { BaseController } from "./base-controller";
+import type { GroupDTO } from "@dwengo-1/common/interfaces/group";
+import type { SubmissionsResponse } from "./submissions";
+import type { QuestionsResponse } from "./questions";
 
 export interface GroupsResponse {
     groups: GroupDTO[];
-} // | TODO id
+}
+
+export interface GroupResponse {
+    group: GroupDTO;
+}
+
+export class GroupController extends BaseController {
+    constructor(classid: string, assignmentNumber: number) {
+        super(`class/${classid}/assignments/${assignmentNumber}/groups`);
+    }
+
+    async getAll(full = true): Promise<GroupsResponse> {
+        return this.get<GroupsResponse>(`/`, { full });
+    }
+
+    async getByNumber(num: number): Promise<GroupResponse> {
+        return this.get<GroupResponse>(`/${num}`);
+    }
+
+    async createGroup(data: GroupDTO): Promise<GroupResponse> {
+        return this.post<GroupResponse>(`/`, data);
+    }
+
+    async deleteGroup(num: number): Promise<GroupResponse> {
+        return this.delete<GroupResponse>(`/${num}`);
+    }
+
+    async updateGroup(num: number, data: Partial<GroupDTO>): Promise<GroupResponse> {
+        return this.put<GroupResponse>(`/${num}`, data);
+    }
+
+    async getSubmissions(groupNumber: number, full = true): Promise<SubmissionsResponse> {
+        return this.get<SubmissionsResponse>(`/${groupNumber}/submissions`, { full });
+    }
+
+    async getQuestions(groupNumber: number, full = true): Promise<QuestionsResponse> {
+        return this.get<QuestionsResponse>(`/${groupNumber}/questions`, { full });
+    }
+}
diff --git a/frontend/src/controllers/questions.ts b/frontend/src/controllers/questions.ts
index 9b0182de..60a51d1a 100644
--- a/frontend/src/controllers/questions.ts
+++ b/frontend/src/controllers/questions.ts
@@ -1,5 +1,38 @@
-import type { QuestionDTO, QuestionId } from "@dwengo-1/interfaces/question";
+import type { QuestionData, QuestionDTO, QuestionId } from "@dwengo-1/common/interfaces/question";
+import { BaseController } from "@/controllers/base-controller.ts";
+import type { LearningObjectIdentifierDTO } from "@dwengo-1/common/interfaces/learning-content";
 
 export interface QuestionsResponse {
     questions: QuestionDTO[] | QuestionId[];
 }
+
+export interface QuestionResponse {
+    question: QuestionDTO;
+}
+
+export class QuestionController extends BaseController {
+    constructor(loId: LearningObjectIdentifierDTO) {
+        this.loId = loId;
+        super(`learningObject/${loId.hruid}/:${loId.version}/questions`);
+    }
+
+    async getAll(full = true): Promise<QuestionsResponse> {
+        return this.get<QuestionsResponse>("/", { lang: this.loId.lang, full });
+    }
+
+    async getBy(sequenceNumber: number): Promise<QuestionResponse> {
+        return this.get<QuestionResponse>(`/${sequenceNumber}`, { lang: this.loId.lang });
+    }
+
+    async create(questionData: QuestionData): Promise<QuestionResponse> {
+        return this.post<QuestionResponse>("/", questionData, { lang: this.loId.lang });
+    }
+
+    async remove(sequenceNumber: number): Promise<QuestionResponse> {
+        return this.delete<QuestionResponse>(`/${sequenceNumber}`, { lang: this.loId.lang });
+    }
+
+    async update(sequenceNumber: number, questionData: QuestionData): Promise<QuestionResponse> {
+        return this.put<QuestionResponse>(`/${sequenceNumber}`, questionData, { lang: this.loId.lang });
+    }
+}
diff --git a/frontend/src/controllers/students.ts b/frontend/src/controllers/students.ts
index b36f1d5a..e9da9c74 100644
--- a/frontend/src/controllers/students.ts
+++ b/frontend/src/controllers/students.ts
@@ -4,8 +4,8 @@ import type { AssignmentsResponse } from "@/controllers/assignments.ts";
 import type { GroupsResponse } from "@/controllers/groups.ts";
 import type { SubmissionsResponse } from "@/controllers/submissions.ts";
 import type { QuestionsResponse } from "@/controllers/questions.ts";
-import type { StudentDTO } from "@dwengo-1/interfaces/student";
-import type { ClassJoinRequestDTO } from "@dwengo-1/interfaces/class-join-request";
+import type { StudentDTO } from "@dwengo-1/common/interfaces/student";
+import type { ClassJoinRequestDTO } from "@dwengo-1/common/interfaces/class-join-request";
 
 export interface StudentsResponse {
     students: StudentDTO[] | string[];
@@ -70,7 +70,7 @@ export class StudentController extends BaseController {
     }
 
     async createJoinRequest(username: string, classId: string): Promise<JoinRequestResponse> {
-        return this.post<JoinRequestResponse>(`/${username}/joinRequests}`, classId);
+        return this.post<JoinRequestResponse>(`/${username}/joinRequests`, { classId });
     }
 
     async deleteJoinRequest(username: string, classId: string): Promise<JoinRequestResponse> {
diff --git a/frontend/src/controllers/submissions.ts b/frontend/src/controllers/submissions.ts
index 99b6ba8d..837d356c 100644
--- a/frontend/src/controllers/submissions.ts
+++ b/frontend/src/controllers/submissions.ts
@@ -1,5 +1,32 @@
-import { type SubmissionDTO, SubmissionDTOId } from "@dwengo-1/interfaces/submission";
+import { BaseController } from "./base-controller";
+import type { SubmissionDTO, SubmissionDTOId } from "@dwengo-1/common/interfaces/submission";
 
 export interface SubmissionsResponse {
     submissions: SubmissionDTO[] | SubmissionDTOId[];
 }
+
+export interface SubmissionResponse {
+    submission: SubmissionDTO;
+}
+
+export class SubmissionController extends BaseController {
+    constructor(classid: string, assignmentNumber: number, groupNumber: number) {
+        super(`class/${classid}/assignments/${assignmentNumber}/groups/${groupNumber}`);
+    }
+
+    async getAll(full = true): Promise<SubmissionsResponse> {
+        return this.get<SubmissionsResponse>(`/`, { full });
+    }
+
+    async getByNumber(submissionNumber: number): Promise<SubmissionResponse> {
+        return this.get<SubmissionResponse>(`/${submissionNumber}`);
+    }
+
+    async createSubmission(data: unknown): Promise<SubmissionResponse> {
+        return this.post<SubmissionResponse>(`/`, data);
+    }
+
+    async deleteSubmission(submissionNumber: number): Promise<SubmissionResponse> {
+        return this.delete<SubmissionResponse>(`/${submissionNumber}`);
+    }
+}
diff --git a/frontend/src/controllers/teachers.ts b/frontend/src/controllers/teachers.ts
index e0d38a6c..973e2b02 100644
--- a/frontend/src/controllers/teachers.ts
+++ b/frontend/src/controllers/teachers.ts
@@ -2,7 +2,7 @@ import { BaseController } from "@/controllers/base-controller.ts";
 import type { JoinRequestResponse, JoinRequestsResponse, StudentsResponse } from "@/controllers/students.ts";
 import type { QuestionsResponse } from "@/controllers/questions.ts";
 import type { ClassesResponse } from "@/controllers/classes.ts";
-import type { TeacherDTO } from "@dwengo-1/interfaces/teacher";
+import type { TeacherDTO } from "@dwengo-1/common/interfaces/teacher";
 
 export interface TeachersResponse {
     teachers: TeacherDTO[] | string[];
diff --git a/frontend/src/controllers/themes.ts b/frontend/src/controllers/themes.ts
index bb76249d..ca173373 100644
--- a/frontend/src/controllers/themes.ts
+++ b/frontend/src/controllers/themes.ts
@@ -1,5 +1,5 @@
 import { BaseController } from "@/controllers/base-controller.ts";
-import type { Theme } from "@dwengo-1/interfaces/theme";
+import type { Theme } from "@dwengo-1/common/interfaces/theme";
 
 export class ThemeController extends BaseController {
     constructor() {
diff --git a/frontend/src/i18n/locale/de.json b/frontend/src/i18n/locale/de.json
index d20154a4..d7bded04 100644
--- a/frontend/src/i18n/locale/de.json
+++ b/frontend/src/i18n/locale/de.json
@@ -17,6 +17,11 @@
     "inclusive": "Inclusiv",
     "sociallyRelevant": "Gesellschaftlich relevant",
     "translate": "übersetzen",
+    "joinClass": "Klasse beitreten",
+    "JoinClassExplanation": "Geben Sie den Code ein, den Ihnen die Lehrkraft mitgeteilt hat, um der Klasse beizutreten.",
+    "invalidFormat": "Ungültiges Format",
+    "submitCode": "senden",
+    "members": "Mitglieder",
     "themes": "Themen",
     "choose-theme": "Wähle ein thema",
     "choose-age": "Alter auswählen",
@@ -51,5 +56,24 @@
     "noLearningPathsFoundDescription": "Es gibt keine Lernpfade, die zu Ihrem Suchbegriff passen.",
     "legendNotCompletedYet": "Noch nicht fertig",
     "legendCompleted": "Fertig",
-    "legendTeacherExclusive": "Information für Lehrkräfte"
+    "legendTeacherExclusive": "Information für Lehrkräfte",
+    "code": "code",
+    "class": "Klasse",
+    "invitations": "Einladungen",
+    "createClass": "Klasse erstellen",
+    "createClassInstructions": "Geben Sie einen Namen für Ihre Klasse ein und klicken Sie auf „Erstellen“. Es erscheint ein Fenster mit einem Code, den Sie kopieren können. Geben Sie diesen Code an Ihre Schüler weiter und sie können Ihrer Klasse beitreten.",
+    "classname": "Klassenname",
+    "EnterNameOfClass": "einen Klassennamen eingeben.",
+    "create": "erstellen",
+    "sender": "Absender",
+    "nameIsMandatory": "Der Klassenname ist ein Pflichtfeld",
+    "onlyUse": "nur Buchstaben, Zahlen, Bindestriche (-) und Unterstriche (_) verwenden",
+    "close": "schließen",
+    "copied": "kopiert!",
+    "accept": "akzeptieren",
+    "deny": "ablehnen",
+    "sent": "sent",
+    "failed": "gescheitert",
+    "wrong": "etwas ist schief gelaufen",
+    "created": "erstellt"
 }
diff --git a/frontend/src/i18n/locale/en.json b/frontend/src/i18n/locale/en.json
index 8d7ed775..171eb1f8 100644
--- a/frontend/src/i18n/locale/en.json
+++ b/frontend/src/i18n/locale/en.json
@@ -29,6 +29,11 @@
     "sociallyRelevant": "Socially relevant",
     "login": "log in",
     "translate": "translate",
+    "joinClass": "Join class",
+    "JoinClassExplanation": "Enter the code the teacher has given you to join the class.",
+    "invalidFormat": "Invalid format.",
+    "submitCode": "submit",
+    "members": "members",
     "themes": "Themes",
     "choose-theme": "Select a theme",
     "choose-age": "Select age",
@@ -51,5 +56,24 @@
         "high-school": "16-18 years old",
         "older": "18 and older"
     },
-    "read-more": "Read more"
+    "read-more": "Read more",
+    "code": "code",
+    "class": "class",
+    "invitations": "invitations",
+    "createClass": "create class",
+    "classname": "classname",
+    "EnterNameOfClass": "Enter a classname.",
+    "create": "create",
+    "sender": "sender",
+    "nameIsMandatory": "classname is mandatory",
+    "onlyUse": "only use letters, numbers, dashes (-) and underscores (_)",
+    "close": "close",
+    "copied": "copied!",
+    "accept": "accept",
+    "deny": "deny",
+    "createClassInstructions": "Enter a name for your class and click on create. A window will appear with a code that you can copy. Give this code to your students and they will be able to join.",
+    "sent": "sent",
+    "failed": "failed",
+    "wrong": "something went wrong",
+    "created": "created"
 }
diff --git a/frontend/src/i18n/locale/fr.json b/frontend/src/i18n/locale/fr.json
index 2dfbb949..a3d3d89b 100644
--- a/frontend/src/i18n/locale/fr.json
+++ b/frontend/src/i18n/locale/fr.json
@@ -29,6 +29,11 @@
     "inclusive": "Inclusif",
     "sociallyRelevant": "Socialement pertinent",
     "translate": "traduire",
+    "joinClass": "Rejoindre une classe",
+    "JoinClassExplanation": "Entrez le code que l'enseignant vous a donné pour rejoindre la classe.",
+    "invalidFormat": "Format non valide.",
+    "submitCode": "envoyer",
+    "members": "membres",
     "themes": "Thèmes",
     "choose-theme": "Choisis un thème",
     "choose-age": "Choisis un âge",
@@ -51,5 +56,24 @@
         "high-school": "16-18 ans",
         "older": "18 et plus"
     },
-    "read-more": "En savoir plus"
+    "read-more": "En savoir plus",
+    "code": "code",
+    "class": "classe",
+    "invitations": "invitations",
+    "createClass": "créer une classe",
+    "createClassInstructions": "Entrez un nom pour votre classe et cliquez sur créer. Une fenêtre apparaît avec un code que vous pouvez copier. Donnez ce code à vos élèves et ils pourront rejoindre votre classe.",
+    "classname": "nom de classe",
+    "EnterNameOfClass": "saisir un nom de classe.",
+    "create": "créer",
+    "sender": "expéditeur",
+    "nameIsMandatory": "le nom de classe est obligatoire",
+    "onlyUse": "n'utiliser que des lettres, des chiffres, des tirets (-) et des traits de soulignement (_)",
+    "close": "fermer",
+    "copied": "copié!",
+    "accept": "accepter",
+    "deny": "refuser",
+    "sent": "envoyé",
+    "failed": "échoué",
+    "wrong": "quelque chose n'a pas fonctionné",
+    "created": "créé"
 }
diff --git a/frontend/src/i18n/locale/nl.json b/frontend/src/i18n/locale/nl.json
index 80cdd8e1..1fbed08d 100644
--- a/frontend/src/i18n/locale/nl.json
+++ b/frontend/src/i18n/locale/nl.json
@@ -29,6 +29,11 @@
     "sociallyRelevant": "Maatschappelijk relevant",
     "login": "log in",
     "translate": "vertalen",
+    "joinClass": "Word lid van een klas",
+    "JoinClassExplanation": "Voer de code in die je van de docent hebt gekregen om lid te worden van de klas.",
+    "invalidFormat": "Ongeldig formaat.",
+    "submitCode": "verzenden",
+    "members": "leden",
     "themes": "Lesthema's",
     "choose-theme": "Kies een thema",
     "choose-age": "Kies een leeftijd",
@@ -51,5 +56,24 @@
         "high-school": "3e graad secundair",
         "older": "Hoger onderwijs"
     },
-    "read-more": "Lees meer"
+    "read-more": "Lees meer",
+    "code": "code",
+    "class": "klas",
+    "invitations": "uitnodigingen",
+    "createClass": "klas aanmaken",
+    "createClassInstructions": "Voer een naam in voor je klas en klik op create. Er verschijnt een venster met een code die je kunt kopiëren. Geef deze code aan je leerlingen en ze kunnen deelnemen aan je klas.",
+    "classname": "klasnaam",
+    "EnterNameOfClass": "Geef een klasnaam op.",
+    "create": "aanmaken",
+    "sender": "afzender",
+    "nameIsMandatory": "klasnaam is verplicht",
+    "onlyUse": "gebruik enkel letters, cijfers, dashes (-) en underscores (_)",
+    "close": "sluiten",
+    "copied": "gekopieerd!",
+    "accept": "accepteren",
+    "deny": "weigeren",
+    "sent": "verzonden",
+    "failed": "mislukt",
+    "wrong": "er ging iets verkeerd",
+    "created": "gecreëerd"
 }
diff --git a/frontend/src/queries/answers.ts b/frontend/src/queries/answers.ts
new file mode 100644
index 00000000..f2d0f9c4
--- /dev/null
+++ b/frontend/src/queries/answers.ts
@@ -0,0 +1,51 @@
+import type { QuestionId } from "@dwengo-1/common/dist/interfaces/question.ts";
+import { type MaybeRefOrGetter, toValue } from "vue";
+import { useMutation, type UseMutationReturnType, useQuery, type UseQueryReturnType } from "@tanstack/vue-query";
+import { AnswerController, type AnswerResponse, type AnswersResponse } from "@/controllers/answers.ts";
+import type { AnswerData } from "@dwengo-1/common/dist/interfaces/answer.ts";
+
+// TODO caching
+
+export function useAnswersQuery(
+    questionId: MaybeRefOrGetter<QuestionId>,
+    full: MaybeRefOrGetter<boolean> = true,
+): UseQueryReturnType<AnswersResponse, Error> {
+    return useQuery({
+        queryFn: async () => new AnswerController(toValue(questionId)).getAll(toValue(full)),
+        enabled: () => Boolean(toValue(questionId)),
+    });
+}
+
+export function useAnswerQuery(
+    questionId: MaybeRefOrGetter<QuestionId>,
+    sequenceNumber: MaybeRefOrGetter<number>,
+): UseQueryReturnType<AnswerResponse, Error> {
+    return useQuery({
+        queryFn: async () => new AnswerController(toValue(questionId)).getBy(toValue(sequenceNumber)),
+        enabled: () => Boolean(toValue(questionId)),
+    });
+}
+
+export function useCreateAnswerMutation(
+    questionId: MaybeRefOrGetter<QuestionId>,
+): UseMutationReturnType<AnswerResponse, Error, AnswerData, unknown> {
+    return useMutation({
+        mutationFn: async (data) => new AnswerController(toValue(questionId)).create(data),
+    });
+}
+
+export function useDeleteAnswerMutation(
+    questionId: MaybeRefOrGetter<QuestionId>,
+): UseMutationReturnType<AnswerResponse, Error, number, unknown> {
+    return useMutation({
+        mutationFn: async (seq) => new AnswerController(toValue(questionId)).remove(seq),
+    });
+}
+
+export function useUpdateAnswerMutation(
+    questionId: MaybeRefOrGetter<QuestionId>,
+): UseMutationReturnType<AnswerResponse, Error, { answerData: AnswerData; seq: number }, unknown> {
+    return useMutation({
+        mutationFn: async (data, seq) => new AnswerController(toValue(questionId)).update(seq, data),
+    });
+}
diff --git a/frontend/src/queries/questions.ts b/frontend/src/queries/questions.ts
new file mode 100644
index 00000000..b69164a4
--- /dev/null
+++ b/frontend/src/queries/questions.ts
@@ -0,0 +1,93 @@
+import { QuestionController, type QuestionResponse, type QuestionsResponse } from "@/controllers/questions.ts";
+import type { QuestionData, QuestionId } from "@dwengo-1/common/interfaces/question";
+import type { LearningObjectIdentifierDTO } from "@dwengo-1/common/interfaces/learning-content";
+import { computed, type MaybeRefOrGetter, toValue } from "vue";
+import {
+    useMutation,
+    type UseMutationReturnType,
+    useQuery,
+    useQueryClient,
+    type UseQueryReturnType,
+} from "@tanstack/vue-query";
+
+export function questionsQueryKey(
+    loId: LearningObjectIdentifierDTO,
+    full: boolean,
+): [string, string, number, string, boolean] {
+    return ["questions", loId.hruid, loId.version, loId.language, full];
+}
+
+export function questionQueryKey(questionId: QuestionId): [string, string, number, string, number] {
+    const loId = questionId.learningObjectIdentifier;
+    return ["question", loId.hruid, loId.version, loId.language, questionId.sequenceNumber];
+}
+
+export function useQuestionsQuery(
+    loId: MaybeRefOrGetter<LearningObjectIdentifierDTO>,
+    full: MaybeRefOrGetter<boolean> = true,
+): UseQueryReturnType<QuestionsResponse, Error> {
+    return useQuery({
+        queryKey: computed(() => questionsQueryKey(toValue(loId), toValue(full))),
+        queryFn: async () => new QuestionController(toValue(loId)).getAll(toValue(full)),
+        enabled: () => Boolean(toValue(loId)),
+    });
+}
+
+export function useQuestionQuery(
+    questionId: MaybeRefOrGetter<QuestionId>,
+): UseQueryReturnType<QuestionResponse, Error> {
+    const loId = toValue(questionId).learningObjectIdentifier;
+    const sequenceNumber = toValue(questionId).sequenceNumber;
+    return useQuery({
+        queryKey: computed(() => questionQueryKey(loId, sequenceNumber)),
+        queryFn: async () => new QuestionController(loId).getBy(sequenceNumber),
+        enabled: () => Boolean(toValue(questionId)),
+    });
+}
+
+export function useCreateQuestionMutation(
+    loId: MaybeRefOrGetter<LearningObjectIdentifierDTO>,
+): UseMutationReturnType<QuestionResponse, Error, QuestionData, unknown> {
+    const queryClient = useQueryClient();
+
+    return useMutation({
+        mutationFn: async (data) => new QuestionController(toValue(loId)).create(data),
+        onSuccess: async () => {
+            await queryClient.invalidateQueries({ queryKey: questionsQueryKey(toValue(loId), true) });
+            await queryClient.invalidateQueries({ queryKey: questionsQueryKey(toValue(loId), false) });
+        },
+    });
+}
+
+export function useUpdateQuestionMutation(
+    questionId: MaybeRefOrGetter<QuestionId>,
+): UseMutationReturnType<QuestionResponse, Error, QuestionData, unknown> {
+    const queryClient = useQueryClient();
+    const loId = toValue(questionId).learningObjectIdentifier;
+    const sequenceNumber = toValue(questionId).sequenceNumber;
+
+    return useMutation({
+        mutationFn: async (data) => new QuestionController(loId).update(sequenceNumber, data),
+        onSuccess: async () => {
+            await queryClient.invalidateQueries({ queryKey: questionsQueryKey(toValue(loId), true) });
+            await queryClient.invalidateQueries({ queryKey: questionsQueryKey(toValue(loId), false) });
+            await queryClient.invalidateQueries({ queryKey: questionQueryKey(toValue(questionId)) });
+        },
+    });
+}
+
+export function useDeleteQuestionMutation(
+    questionId: MaybeRefOrGetter<QuestionId>,
+): UseMutationReturnType<QuestionResponse, Error, void, unknown> {
+    const queryClient = useQueryClient();
+    const loId = toValue(questionId).learningObjectIdentifier;
+    const sequenceNumber = toValue(questionId).sequenceNumber;
+    return useMutation({
+        mutationFn: async () => new QuestionController(loId).remove(sequenceNumber),
+        onSuccess: async () => {
+            await queryClient.invalidateQueries({ queryKey: questionsQueryKey(toValue(loId), true) });
+            await queryClient.invalidateQueries({ queryKey: questionsQueryKey(toValue(loId), false) });
+            await queryClient.invalidateQueries({ queryKey: questionQueryKey(toValue(questionId)) });
+        },
+    });
+}
diff --git a/frontend/src/queries/students.ts b/frontend/src/queries/students.ts
index 822083d9..5b01e3c5 100644
--- a/frontend/src/queries/students.ts
+++ b/frontend/src/queries/students.ts
@@ -19,7 +19,7 @@ import type { AssignmentsResponse } from "@/controllers/assignments.ts";
 import type { GroupsResponse } from "@/controllers/groups.ts";
 import type { SubmissionsResponse } from "@/controllers/submissions.ts";
 import type { QuestionsResponse } from "@/controllers/questions.ts";
-import type { StudentDTO } from "@dwengo-1/interfaces/student";
+import type { StudentDTO } from "@dwengo-1/common/interfaces/student";
 
 const studentController = new StudentController();
 
@@ -179,7 +179,7 @@ export function useCreateJoinRequestMutation(): UseMutationReturnType<
         mutationFn: async ({ username, classId }) => studentController.createJoinRequest(username, classId),
         onSuccess: async (newJoinRequest) => {
             await queryClient.invalidateQueries({
-                queryKey: studentJoinRequestsQueryKey(newJoinRequest.request.requester),
+                queryKey: studentJoinRequestsQueryKey(newJoinRequest.request.requester.username),
             });
         },
     });
@@ -196,7 +196,7 @@ export function useDeleteJoinRequestMutation(): UseMutationReturnType<
     return useMutation({
         mutationFn: async ({ username, classId }) => studentController.deleteJoinRequest(username, classId),
         onSuccess: async (deletedJoinRequest) => {
-            const username = deletedJoinRequest.request.requester;
+            const username = deletedJoinRequest.request.requester.username;
             const classId = deletedJoinRequest.request.class;
             await queryClient.invalidateQueries({ queryKey: studentJoinRequestsQueryKey(username) });
             await queryClient.invalidateQueries({ queryKey: studentJoinRequestQueryKey(username, classId) });
diff --git a/frontend/src/queries/teachers.ts b/frontend/src/queries/teachers.ts
index 778b2cba..50d61f6c 100644
--- a/frontend/src/queries/teachers.ts
+++ b/frontend/src/queries/teachers.ts
@@ -1,11 +1,17 @@
 import { computed, toValue } from "vue";
 import type { MaybeRefOrGetter } from "vue";
-import { useMutation, useQuery, useQueryClient, UseMutationReturnType, UseQueryReturnType } from "@tanstack/vue-query";
+import {
+    useMutation,
+    useQuery,
+    useQueryClient,
+    type UseMutationReturnType,
+    type UseQueryReturnType,
+} from "@tanstack/vue-query";
 import { TeacherController, type TeacherResponse, type TeachersResponse } from "@/controllers/teachers.ts";
 import type { ClassesResponse } from "@/controllers/classes.ts";
 import type { JoinRequestResponse, JoinRequestsResponse, StudentsResponse } from "@/controllers/students.ts";
 import type { QuestionsResponse } from "@/controllers/questions.ts";
-import type { TeacherDTO } from "@dwengo-1/interfaces/teacher";
+import type { TeacherDTO } from "@dwengo-1/common/interfaces/teacher";
 import { studentJoinRequestQueryKey, studentJoinRequestsQueryKey } from "@/queries/students.ts";
 
 const teacherController = new TeacherController();
diff --git a/frontend/src/views/classes/SingleClass.vue b/frontend/src/views/classes/SingleClass.vue
index 1a35a59f..6a6b2f12 100644
--- a/frontend/src/views/classes/SingleClass.vue
+++ b/frontend/src/views/classes/SingleClass.vue
@@ -1,7 +1,224 @@
-<script setup lang="ts"></script>
+<script setup lang="ts">
+    import { useI18n } from "vue-i18n";
+    import authState from "@/services/auth/auth-service.ts";
+    import { onMounted, ref } from "vue";
+    import type { ClassDTO } from "@dwengo-1/common/interfaces/class";
+    import { useRoute } from "vue-router";
+    import { ClassController, type ClassResponse } from "@/controllers/classes";
+    import type { StudentsResponse } from "@/controllers/students";
+    import type { StudentDTO } from "@dwengo-1/common/interfaces/student";
 
+    const { t } = useI18n();
+
+    // Username of logged in teacher
+    const username = ref<string | undefined>(undefined);
+    const classController: ClassController = new ClassController();
+
+    // Find class id from route
+    const route = useRoute();
+    const classId: string = route.params.id as string;
+
+    const isLoading = ref(true);
+    const currentClass = ref<ClassDTO | undefined>(undefined);
+    const students = ref<StudentDTO[]>([]);
+
+    // Find the username of the logged in user so it can be used to fetch other information
+    // When loading the page
+    onMounted(async () => {
+        const userObject = await authState.loadUser();
+        username.value = userObject?.profile?.preferred_username ?? undefined;
+
+        // Get class of which information should be shown
+        const classResponse: ClassResponse = await classController.getById(classId);
+        if (classResponse && classResponse.class) {
+            currentClass.value = classResponse.class;
+            isLoading.value = false;
+        }
+
+        // Fetch all students of the class
+        const studentsResponse: StudentsResponse = await classController.getStudents(classId);
+        if (studentsResponse && studentsResponse.students) students.value = studentsResponse.students as StudentDTO[];
+    });
+
+    // TODO: Boolean that handles visibility for dialogs
+    // Popup to verify removing student
+    const dialog = ref(false);
+    const selectedStudent = ref<StudentDTO | null>(null);
+
+    function showPopup(s: StudentDTO): void {
+        selectedStudent.value = s;
+        dialog.value = true;
+    }
+
+    // Remove student from class
+    function removeStudentFromclass(): void {
+        dialog.value = false;
+    }
+</script>
 <template>
-    <main></main>
-</template>
+    <main>
+        <div
+            v-if="isLoading"
+            class="text-center py-10"
+        >
+            <v-progress-circular
+                indeterminate
+                color="primary"
+            />
+            <p>Loading...</p>
+        </div>
+        <div v-else>
+            <h1 class="title">{{ currentClass!.displayName }}</h1>
+            <v-container
+                fluid
+                class="ma-4"
+            >
+                <v-row
+                    no-gutters
+                    fluid
+                >
+                    <v-col
+                        cols="12"
+                        sm="6"
+                        md="6"
+                    >
+                        <v-table class="table">
+                            <thead>
+                                <tr>
+                                    <th class="header">{{ t("students") }}</th>
+                                    <th class="header"></th>
+                                </tr>
+                            </thead>
+                            <tbody>
+                                <tr
+                                    v-for="s in students"
+                                    :key="s.id"
+                                >
+                                    <td>
+                                        {{ s.firstName + " " + s.lastName }}
+                                    </td>
+                                    <td>
+                                        <v-btn @click="showPopup"> {{ t("remove") }} </v-btn>
+                                    </td>
+                                </tr>
+                            </tbody>
+                        </v-table>
+                    </v-col>
+                </v-row>
+            </v-container>
+        </div>
+        <v-dialog
+            v-model="dialog"
+            max-width="400px"
+        >
+            <v-card>
+                <v-card-title class="headline">{{ t("areusure") }}</v-card-title>
 
-<style scoped></style>
+                <v-card-actions>
+                    <v-spacer></v-spacer>
+                    <v-btn
+                        text
+                        @click="dialog = false"
+                    >
+                        {{ t("cancel") }}
+                    </v-btn>
+                    <v-btn
+                        text
+                        @click="removeStudentFromclass"
+                        >{{ t("yes") }}</v-btn
+                    >
+                </v-card-actions>
+            </v-card>
+        </v-dialog>
+    </main>
+</template>
+<style scoped>
+    .header {
+        font-weight: bold !important;
+        background-color: #0e6942;
+        color: white;
+        padding: 10px;
+    }
+
+    table thead th:first-child {
+        border-top-left-radius: 10px;
+    }
+
+    .table thead th:last-child {
+        border-top-right-radius: 10px;
+    }
+
+    .table tbody tr:nth-child(odd) {
+        background-color: white;
+    }
+
+    .table tbody tr:nth-child(even) {
+        background-color: #f6faf2;
+    }
+
+    td,
+    th {
+        border-bottom: 1px solid #0e6942;
+        border-top: 1px solid #0e6942;
+    }
+
+    .table {
+        width: 90%;
+        padding-top: 10px;
+        border-collapse: collapse;
+    }
+
+    h1 {
+        color: #0e6942;
+        text-transform: uppercase;
+        font-weight: bolder;
+        padding-top: 2%;
+        font-size: 50px;
+    }
+
+    h2 {
+        color: #0e6942;
+        font-size: 30px;
+    }
+
+    .join {
+        display: flex;
+        flex-direction: column;
+        gap: 20px;
+        margin-top: 50px;
+    }
+
+    .link {
+        color: #0b75bb;
+        text-decoration: underline;
+    }
+
+    main {
+        margin-left: 30px;
+    }
+
+    @media screen and (max-width: 800px) {
+        h1 {
+            text-align: center;
+            padding-left: 0;
+        }
+
+        .join {
+            text-align: center;
+            align-items: center;
+            margin-left: 0;
+        }
+
+        .sheet {
+            width: 100%;
+        }
+
+        main {
+            display: flex;
+            flex-direction: column;
+            align-items: center;
+            justify-content: center;
+            margin: 5px;
+        }
+    }
+</style>
diff --git a/frontend/src/views/classes/StudentClasses.vue b/frontend/src/views/classes/StudentClasses.vue
index 1a35a59f..2bfdc1b8 100644
--- a/frontend/src/views/classes/StudentClasses.vue
+++ b/frontend/src/views/classes/StudentClasses.vue
@@ -1,7 +1,380 @@
-<script setup lang="ts"></script>
+<script setup lang="ts">
+    import { useI18n } from "vue-i18n";
+    import authState from "@/services/auth/auth-service.ts";
+    import { computed, onMounted, ref, type ComputedRef } from "vue";
+    import { validate, version } from "uuid";
+    import type { ClassDTO } from "@dwengo-1/common/interfaces/class";
+    import { useCreateJoinRequestMutation, useStudentClassesQuery } from "@/queries/students";
+    import type { StudentDTO } from "@dwengo-1/common/interfaces/student";
+    import { StudentController } from "@/controllers/students";
+    import type { TeacherDTO } from "@dwengo-1/common/interfaces/teacher";
+    import { TeacherController } from "@/controllers/teachers";
 
+    const { t } = useI18n();
+    const studentController: StudentController = new StudentController();
+    const teacherController: TeacherController = new TeacherController();
+
+    // Username of logged in student
+    const username = ref<string | undefined>(undefined);
+
+    // Find the username of the logged in user so it can be used to fetch other information
+    // When loading the page
+    onMounted(async () => {
+        const userObject = await authState.loadUser();
+        username.value = userObject?.profile?.preferred_username ?? undefined;
+    });
+
+    // Fetch all classes of the logged in student
+    const { data: classesResponse, isLoading, error } = useStudentClassesQuery(username);
+
+    // Empty list when classes are not yet loaded, else the list of classes of the user
+    const classes: ComputedRef<ClassDTO[]> = computed(() => {
+        // The classes are not yet fetched
+        if (!classesResponse.value) {
+            return [];
+        }
+        // The user has no classes
+        if (classesResponse.value.classes.length === 0) {
+            return [];
+        }
+        return classesResponse.value.classes as ClassDTO[];
+    });
+
+    // Students of selected class are shown when logged in student presses on the member count
+    const selectedClass = ref<ClassDTO | null>(null);
+    const students = ref<StudentDTO[]>([]);
+    const teachers = ref<TeacherDTO[]>([]);
+    const getStudents = ref(false);
+
+    // Boolean that handles visibility for dialogs
+    // Clicking on membercount will show a dialog with all members
+    const dialog = ref(false);
+
+    // Function to display all members of a class in a dialog
+    async function openStudentDialog(c: ClassDTO): Promise<void> {
+        selectedClass.value = c;
+
+        // Clear previous value
+        getStudents.value = true;
+        students.value = [];
+        dialog.value = true;
+
+        // Fetch students from their usernames to display their full names
+        const studentDTOs: (StudentDTO | null)[] = await Promise.all(
+            c.students.map(async (uid) => {
+                try {
+                    const res = await studentController.getByUsername(uid);
+                    return res.student;
+                } catch (_) {
+                    return null;
+                }
+            }),
+        );
+
+        // Only show students that are not fetched ass *null*
+        students.value = studentDTOs.filter(Boolean) as StudentDTO[];
+    }
+
+    async function openTeacherDialog(c: ClassDTO): Promise<void> {
+        selectedClass.value = c;
+
+        // Clear previous value
+        getStudents.value = false;
+        teachers.value = [];
+        dialog.value = true;
+
+        // Fetch names of teachers
+        const teacherDTOs: (TeacherDTO | null)[] = await Promise.all(
+            c.teachers.map(async (uid) => {
+                try {
+                    const res = await teacherController.getByUsername(uid);
+                    return res.teacher;
+                } catch (_) {
+                    return null;
+                }
+            }),
+        );
+
+        teachers.value = teacherDTOs.filter(Boolean) as TeacherDTO[];
+    }
+
+    // Hold the code a student gives in to join a class
+    const code = ref<string>("");
+
+    // The code a student sends in to join a class needs to be formatted as v4 to be valid
+    // These rules are used to display a message to the user if they use a code that has an invalid format
+    const codeRules = [
+        (value: string | undefined): string | boolean => {
+            if (value === undefined || value === "") {
+                return true;
+            } else if (value !== undefined && validate(value) && version(value) === 4) {
+                return true;
+            }
+            return t("invalidFormat");
+        },
+    ];
+
+    // Used to send the actual class join request
+    const { mutate } = useCreateJoinRequestMutation();
+
+    // Function called when a student submits a code to join a class
+    function submitCode(): void {
+        // Check if the code is valid
+        if (code.value !== undefined && validate(code.value) && version(code.value) === 4) {
+            mutate(
+                { username: username.value!, classId: code.value },
+                {
+                    onSuccess: () => {
+                        showSnackbar(t("sent"), "success");
+                    },
+                    onError: (e) => {
+                        showSnackbar(t("failed") + ": " + e.message, "error");
+                    },
+                },
+            );
+            code.value = "";
+        }
+    }
+
+    const snackbar = ref({
+        visible: false,
+        message: "",
+        color: "success",
+    });
+
+    function showSnackbar(message: string, color: string): void {
+        snackbar.value.message = message;
+        snackbar.value.color = color;
+        snackbar.value.visible = true;
+    }
+</script>
 <template>
-    <main></main>
-</template>
+    <main>
+        <div
+            v-if="isLoading"
+            class="text-center py-10"
+        >
+            <v-progress-circular
+                indeterminate
+                color="primary"
+            />
+            <p>Loading...</p>
+        </div>
 
-<style scoped></style>
+        <div
+            v-else-if="error"
+            class="text-center py-10 text-error"
+        >
+            <v-icon large>mdi-alert-circle</v-icon>
+            <p>Error loading: {{ error.message }}</p>
+        </div>
+        <div v-else>
+            <h1 class="title">{{ t("classes") }}</h1>
+            <v-container
+                fluid
+                class="ma-4"
+            >
+                <v-row
+                    no-gutters
+                    fluid
+                >
+                    <v-col
+                        cols="12"
+                        sm="6"
+                        md="6"
+                    >
+                        <v-table class="table">
+                            <thead>
+                                <tr>
+                                    <th class="header">{{ t("classes") }}</th>
+                                    <th class="header">{{ t("teachers") }}</th>
+                                    <th class="header">{{ t("members") }}</th>
+                                </tr>
+                            </thead>
+                            <tbody>
+                                <tr
+                                    v-for="c in classes"
+                                    :key="c.id"
+                                >
+                                    <td>{{ c.displayName }}</td>
+                                    <td
+                                        class="link"
+                                        @click="openTeacherDialog(c)"
+                                    >
+                                        {{ c.teachers.length }}
+                                    </td>
+                                    <td
+                                        class="link"
+                                        @click="openStudentDialog(c)"
+                                    >
+                                        {{ c.students.length }}
+                                    </td>
+                                </tr>
+                            </tbody>
+                        </v-table>
+                    </v-col>
+                </v-row>
+            </v-container>
+
+            <v-dialog
+                v-model="dialog"
+                width="400"
+            >
+                <v-card>
+                    <v-card-title> {{ selectedClass?.displayName }} </v-card-title>
+                    <v-card-text>
+                        <ul v-if="getStudents">
+                            <li
+                                v-for="student in students"
+                                :key="student.username"
+                            >
+                                {{ student.firstName + " " + student.lastName }}
+                            </li>
+                        </ul>
+                        <ul v-else>
+                            <li
+                                v-for="teacher in teachers"
+                                :key="teacher.username"
+                            >
+                                {{ teacher.firstName + " " + teacher.lastName }}
+                            </li>
+                        </ul>
+                    </v-card-text>
+                    <v-card-actions>
+                        <v-btn
+                            color="primary"
+                            @click="dialog = false"
+                            >Close</v-btn
+                        >
+                    </v-card-actions>
+                </v-card>
+            </v-dialog>
+            <div>
+                <div class="join">
+                    <h2>{{ t("joinClass") }}</h2>
+                    <p>{{ t("JoinClassExplanation") }}</p>
+
+                    <v-sheet
+                        class="pa-4 sheet"
+                        max-width="400"
+                    >
+                        <v-form @submit.prevent>
+                            <v-text-field
+                                label="CODE"
+                                v-model="code"
+                                placeholder="XXXXXXXX-XXXX-4XXX-XXXX-XXXXXXXXXXXX"
+                                :rules="codeRules"
+                                variant="outlined"
+                            ></v-text-field>
+                            <v-btn
+                                class="mt-4"
+                                color="#f6faf2"
+                                type="submit"
+                                @click="submitCode"
+                                block
+                                >{{ t("submitCode") }}</v-btn
+                            >
+                        </v-form>
+                    </v-sheet>
+                </div>
+            </div>
+        </div>
+        <v-snackbar
+            v-model="snackbar.visible"
+            :color="snackbar.color"
+            timeout="3000"
+        >
+            {{ snackbar.message }}
+        </v-snackbar>
+    </main>
+</template>
+<style scoped>
+    .header {
+        font-weight: bold !important;
+        background-color: #0e6942;
+        color: white;
+        padding: 10px;
+    }
+
+    table thead th:first-child {
+        border-top-left-radius: 10px;
+    }
+
+    .table thead th:last-child {
+        border-top-right-radius: 10px;
+    }
+
+    .table tbody tr:nth-child(odd) {
+        background-color: white;
+    }
+
+    .table tbody tr:nth-child(even) {
+        background-color: #f6faf2;
+    }
+
+    td,
+    th {
+        border-bottom: 1px solid #0e6942;
+        border-top: 1px solid #0e6942;
+    }
+
+    .table {
+        width: 90%;
+        padding-top: 10px;
+        border-collapse: collapse;
+    }
+
+    h1 {
+        color: #0e6942;
+        text-transform: uppercase;
+        font-weight: bolder;
+        padding-top: 2%;
+        font-size: 50px;
+    }
+
+    h2 {
+        color: #0e6942;
+        font-size: 30px;
+    }
+
+    .join {
+        display: flex;
+        flex-direction: column;
+        gap: 20px;
+        margin-top: 50px;
+    }
+
+    .link {
+        color: #0b75bb;
+        text-decoration: underline;
+    }
+
+    main {
+        margin-left: 30px;
+    }
+
+    @media screen and (max-width: 800px) {
+        h1 {
+            text-align: center;
+            padding-left: 0;
+        }
+
+        .join {
+            text-align: center;
+            align-items: center;
+            margin-left: 0;
+        }
+
+        .sheet {
+            width: 100%;
+        }
+
+        main {
+            display: flex;
+            flex-direction: column;
+            align-items: center;
+            justify-content: center;
+            margin: 5px;
+        }
+    }
+</style>
diff --git a/frontend/src/views/classes/TeacherClasses.vue b/frontend/src/views/classes/TeacherClasses.vue
index 1a35a59f..ae673d99 100644
--- a/frontend/src/views/classes/TeacherClasses.vue
+++ b/frontend/src/views/classes/TeacherClasses.vue
@@ -1,7 +1,404 @@
-<script setup lang="ts"></script>
+<script setup lang="ts">
+    import { useI18n } from "vue-i18n";
+    import authState from "@/services/auth/auth-service.ts";
+    import { computed, onMounted, ref, type ComputedRef } from "vue";
+    import type { TeacherDTO } from "@dwengo-1/common/interfaces/teacher";
+    import type { ClassDTO } from "@dwengo-1/common/interfaces/class";
+    import type { TeacherInvitationDTO } from "@dwengo-1/common/interfaces/teacher-invitation";
+    import { useTeacherClassesQuery } from "@/queries/teachers";
+    import { ClassController, type ClassResponse } from "@/controllers/classes";
 
+    const { t } = useI18n();
+    const classController = new ClassController();
+
+    // Username of logged in teacher
+    const username = ref<string | undefined>(undefined);
+
+    // Find the username of the logged in user so it can be used to fetch other information
+    // When loading the page
+    onMounted(async () => {
+        const userObject = await authState.loadUser();
+        username.value = userObject?.profile?.preferred_username ?? undefined;
+    });
+
+    // Fetch all classes of the logged in teacher
+    const { data: classesResponse, isLoading, error, refetch } = useTeacherClassesQuery(username, true);
+
+    // Empty list when classes are not yet loaded, else the list of classes of the user
+    const classes: ComputedRef<ClassDTO[]> = computed(() => {
+        // The classes are not yet fetched
+        if (!classesResponse.value) {
+            return [];
+        }
+        // The user has no classes
+        if (classesResponse.value.classes.length === 0) {
+            return [];
+        }
+        return classesResponse.value.classes as ClassDTO[];
+    });
+
+    // Boolean that handles visibility for dialogs
+    // Creating a class will generate a popup with the generated code
+    const dialog = ref(false);
+
+    // Code generated when new class was created
+    const code = ref<string>("");
+
+    // TODO: waiting on frontend controllers
+    const invitations = ref<TeacherInvitationDTO[]>([]);
+
+    // Function to handle a accepted invitation request
+    function acceptRequest(): void {
+        //TODO: avoid linting issues when merging by filling the function
+        invitations.value = [];
+    }
+
+    // Function to handle a denied invitation request
+    function denyRequest(): void {
+        //TODO: avoid linting issues when merging by filling the function
+        invitations.value = [];
+    }
+
+    // Teacher should be able to set a displayname when making a class
+    const className = ref<string>("");
+
+    // The name can only contain dash, underscore letters and numbers
+    // These rules are used to display a message to the user if the name is not valid
+    const nameRules = [
+        (value: string | undefined): string | boolean => {
+            if (!value) return true;
+            if (value && /^[a-zA-Z0-9_-]+$/.test(value)) return true;
+            return t("onlyUse");
+        },
+    ];
+
+    // Function called when a teacher creates a class
+    async function createClass(): Promise<void> {
+        // Check if the class name is valid
+        if (className.value && className.value.length > 0 && /^[a-zA-Z0-9_-]+$/.test(className.value)) {
+            try {
+                const classDto: ClassDTO = {
+                    id: "",
+                    displayName: className.value,
+                    teachers: [username.value!],
+                    students: [],
+                    joinRequests: [],
+                };
+                const classResponse: ClassResponse = await classController.createClass(classDto);
+                const createdClass: ClassDTO = classResponse.class;
+                code.value = createdClass.id;
+                dialog.value = true;
+                showSnackbar(t("created"), "success");
+
+                // Reload the table with classes so the new class appears
+                await refetch();
+            } catch (_) {
+                showSnackbar(t("wrong"), "error");
+            }
+        }
+        if (!className.value || className.value === "") {
+            showSnackbar(t("name is mandatory"), "error");
+        }
+    }
+
+    const snackbar = ref({
+        visible: false,
+        message: "",
+        color: "success",
+    });
+
+    function showSnackbar(message: string, color: string): void {
+        snackbar.value.message = message;
+        snackbar.value.color = color;
+        snackbar.value.visible = true;
+    }
+
+    // Show the teacher, copying of the code was a successs
+    const copied = ref(false);
+
+    // Copy the generated code to the clipboard
+    async function copyToClipboard(): Promise<void> {
+        await navigator.clipboard.writeText(code.value);
+        copied.value = true;
+    }
+</script>
 <template>
-    <main></main>
-</template>
+    <main>
+        <div
+            v-if="isLoading"
+            class="text-center py-10"
+        >
+            <v-progress-circular
+                indeterminate
+                color="primary"
+            />
+            <p>Loading...</p>
+        </div>
 
-<style scoped></style>
+        <div
+            v-else-if="error"
+            class="text-center py-10 text-error"
+        >
+            <v-icon large>mdi-alert-circle</v-icon>
+            <p>Error loading: {{ error.message }}</p>
+        </div>
+        <div v-else>
+            <h1 class="title">{{ t("classes") }}</h1>
+            <v-container
+                fluid
+                class="ma-4"
+            >
+                <v-row
+                    no-gutters
+                    fluid
+                >
+                    <v-col
+                        cols="12"
+                        sm="6"
+                        md="6"
+                    >
+                        <v-table class="table">
+                            <thead>
+                                <tr>
+                                    <th class="header">{{ t("classes") }}</th>
+                                    <th class="header">
+                                        {{ t("code") }}
+                                    </th>
+                                    <th class="header">{{ t("members") }}</th>
+                                </tr>
+                            </thead>
+                            <tbody>
+                                <tr
+                                    v-for="c in classes"
+                                    :key="c.id"
+                                >
+                                    <td>
+                                        <v-btn
+                                            :to="`/class/${c.id}`"
+                                            variant="text"
+                                        >
+                                            {{ c.displayName }}
+                                            <v-icon end> mdi-menu-right </v-icon>
+                                        </v-btn>
+                                    </td>
+                                    <td>{{ c.id }}</td>
+                                    <td>{{ c.students.length }}</td>
+                                </tr>
+                            </tbody>
+                        </v-table>
+                    </v-col>
+                    <v-col
+                        cols="12"
+                        sm="6"
+                        md="6"
+                    >
+                        <div>
+                            <h2>{{ t("createClass") }}</h2>
+
+                            <v-sheet
+                                class="pa-4 sheet"
+                                max-width="600px"
+                            >
+                                <p>{{ t("createClassInstructions") }}</p>
+                                <v-form @submit.prevent>
+                                    <v-text-field
+                                        class="mt-4"
+                                        :label="`${t('classname')}`"
+                                        v-model="className"
+                                        :placeholder="`${t('EnterNameOfClass')}`"
+                                        :rules="nameRules"
+                                        variant="outlined"
+                                    ></v-text-field>
+                                    <v-btn
+                                        class="mt-4"
+                                        color="#f6faf2"
+                                        type="submit"
+                                        @click="createClass"
+                                        block
+                                        >{{ t("create") }}</v-btn
+                                    >
+                                </v-form>
+                            </v-sheet>
+                            <v-container>
+                                <v-dialog
+                                    v-model="dialog"
+                                    max-width="400px"
+                                >
+                                    <v-card>
+                                        <v-card-title class="headline">code</v-card-title>
+                                        <v-card-text>
+                                            <v-text-field
+                                                v-model="code"
+                                                readonly
+                                                append-inner-icon="mdi-content-copy"
+                                                @click:append-inner="copyToClipboard"
+                                            ></v-text-field>
+                                            <v-slide-y-transition>
+                                                <div
+                                                    v-if="copied"
+                                                    class="text-center mt-2"
+                                                >
+                                                    {{ t("copied") }}
+                                                </div>
+                                            </v-slide-y-transition>
+                                        </v-card-text>
+                                        <v-card-actions>
+                                            <v-spacer></v-spacer>
+                                            <v-btn
+                                                text
+                                                @click="
+                                                    dialog = false;
+                                                    copied = false;
+                                                "
+                                            >
+                                                {{ t("close") }}
+                                            </v-btn>
+                                        </v-card-actions>
+                                    </v-card>
+                                </v-dialog>
+                            </v-container>
+                        </div>
+                    </v-col>
+                </v-row>
+            </v-container>
+
+            <h1 class="title">
+                {{ t("invitations") }}
+            </h1>
+            <v-table class="table">
+                <thead>
+                    <tr>
+                        <th class="header">{{ t("class") }}</th>
+                        <th class="header">{{ t("sender") }}</th>
+                        <th class="header"></th>
+                    </tr>
+                </thead>
+                <tbody>
+                    <tr
+                        v-for="i in invitations"
+                        :key="(i.class as ClassDTO).id"
+                    >
+                        <td>
+                            {{ (i.class as ClassDTO).displayName }}
+                        </td>
+                        <td>{{ (i.sender as TeacherDTO).firstName + " " + (i.sender as TeacherDTO).lastName }}</td>
+                        <td class="text-right">
+                            <div>
+                                <v-btn
+                                    color="green"
+                                    @click="acceptRequest"
+                                    class="mr-2"
+                                >
+                                    {{ t("accept") }}
+                                </v-btn>
+                                <v-btn
+                                    color="red"
+                                    @click="denyRequest"
+                                >
+                                    {{ t("deny") }}
+                                </v-btn>
+                            </div>
+                        </td>
+                    </tr>
+                </tbody>
+            </v-table>
+        </div>
+        <v-snackbar
+            v-model="snackbar.visible"
+            :color="snackbar.color"
+            timeout="3000"
+        >
+            {{ snackbar.message }}
+        </v-snackbar>
+    </main>
+</template>
+<style scoped>
+    .header {
+        font-weight: bold !important;
+        background-color: #0e6942;
+        color: white;
+        padding: 10px;
+    }
+
+    table thead th:first-child {
+        border-top-left-radius: 10px;
+    }
+
+    .table thead th:last-child {
+        border-top-right-radius: 10px;
+    }
+
+    .table tbody tr:nth-child(odd) {
+        background-color: white;
+    }
+
+    .table tbody tr:nth-child(even) {
+        background-color: #f6faf2;
+    }
+
+    td,
+    th {
+        border-bottom: 1px solid #0e6942;
+        border-top: 1px solid #0e6942;
+    }
+
+    .table {
+        width: 90%;
+        padding-top: 10px;
+        border-collapse: collapse;
+    }
+
+    h1 {
+        color: #0e6942;
+        text-transform: uppercase;
+        font-weight: bolder;
+        padding-top: 2%;
+        font-size: 50px;
+    }
+
+    h2 {
+        color: #0e6942;
+        font-size: 30px;
+    }
+
+    .join {
+        display: flex;
+        flex-direction: column;
+        gap: 20px;
+        margin-top: 50px;
+    }
+
+    .link {
+        color: #0b75bb;
+        text-decoration: underline;
+    }
+
+    main {
+        margin-left: 30px;
+    }
+
+    @media screen and (max-width: 800px) {
+        h1 {
+            text-align: center;
+            padding-left: 0;
+        }
+
+        .join {
+            text-align: center;
+            align-items: center;
+            margin-left: 0;
+        }
+
+        .sheet {
+            width: 100%;
+        }
+
+        main {
+            display: flex;
+            flex-direction: column;
+            align-items: center;
+            justify-content: center;
+            margin: 5px;
+        }
+    }
+</style>
diff --git a/frontend/src/views/classes/UserClasses.vue b/frontend/src/views/classes/UserClasses.vue
index 1a35a59f..566bd02a 100644
--- a/frontend/src/views/classes/UserClasses.vue
+++ b/frontend/src/views/classes/UserClasses.vue
@@ -1,7 +1,17 @@
-<script setup lang="ts"></script>
+<script setup lang="ts">
+    import authState from "@/services/auth/auth-service.ts";
+    import TeacherClasses from "./TeacherClasses.vue";
+    import StudentClasses from "./StudentClasses.vue";
+
+    // Determine if role is student or teacher to render correct view
+    const role: string = authState.authState.activeRole!;
+</script>
 
 <template>
-    <main></main>
+    <main>
+        <TeacherClasses v-if="role === 'teacher'"></TeacherClasses>
+        <StudentClasses v-else></StudentClasses>
+    </main>
 </template>
 
 <style scoped></style>