diff --git a/backend/src/controllers/auth.ts b/backend/src/controllers/auth.ts
index 14b05dc8..6395715d 100644
--- a/backend/src/controllers/auth.ts
+++ b/backend/src/controllers/auth.ts
@@ -2,10 +2,10 @@ import { UnauthorizedException } from '../exceptions/unauthorized-exception.js';
 import { getLogger } from '../logging/initalize.js';
 import { AuthenticatedRequest } from '../middleware/auth/authenticated-request.js';
 import { envVars, getEnvVar } from '../util/envVars.js';
-import {createOrUpdateStudent, createStudent} from "../services/students";
-import {AuthenticationInfo} from "../middleware/auth/authentication-info";
-import {Request, Response} from "express";
-import {createOrUpdateTeacher, createTeacher} from "../services/teachers";
+import { createOrUpdateStudent, createStudent } from '../services/students';
+import { AuthenticationInfo } from '../middleware/auth/authentication-info';
+import { Request, Response } from 'express';
+import { createOrUpdateTeacher, createTeacher } from '../services/teachers';
 
 interface FrontendIdpConfig {
     authority: string;
@@ -47,20 +47,26 @@ export function handleGetFrontendAuthConfig(_req: Request, res: Response): void
 
 export async function handleHello(req: AuthenticatedRequest): Promise<void> {
     const auth: AuthenticationInfo = req.auth!;
-    if (auth.accountType === "teacher") {
-        await createTeacher({
-            id: auth.username,
-            username: auth.username,
-            firstName: auth.firstName ?? "",
-            lastName: auth.lastName ?? "",
-        }, true);
+    if (auth.accountType === 'teacher') {
+        await createTeacher(
+            {
+                id: auth.username,
+                username: auth.username,
+                firstName: auth.firstName ?? '',
+                lastName: auth.lastName ?? '',
+            },
+            true
+        );
     } else {
-        await createStudent({
-            id: auth.username,
-            username: auth.username,
-            firstName: auth.firstName ?? "",
-            lastName: auth.lastName ?? "",
-        }, true);
+        await createStudent(
+            {
+                id: auth.username,
+                username: auth.username,
+                firstName: auth.firstName ?? '',
+                lastName: auth.lastName ?? '',
+            },
+            true
+        );
     }
 }
 
diff --git a/backend/src/controllers/teacher-invitations.ts b/backend/src/controllers/teacher-invitations.ts
index 0a8b89c0..f1350660 100644
--- a/backend/src/controllers/teacher-invitations.ts
+++ b/backend/src/controllers/teacher-invitations.ts
@@ -2,7 +2,7 @@ import { Request, Response } from 'express';
 import { requireFields } from './error-helper.js';
 import { createInvitation, deleteInvitation, getAllInvitations, getInvitation, updateInvitation } from '../services/teacher-invitations.js';
 import { TeacherInvitationData } from '@dwengo-1/common/interfaces/teacher-invitation';
-import {ConflictException} from "../exceptions/conflict-exception";
+import { ConflictException } from '../exceptions/conflict-exception';
 
 export async function getAllInvitationsHandler(req: Request, res: Response): Promise<void> {
     const username = req.params.username;
@@ -31,8 +31,8 @@ export async function createInvitationHandler(req: Request, res: Response): Prom
     const classId = req.body.class;
     requireFields({ sender, receiver, classId });
 
-    if (sender === receiver){
-        throw new ConflictException("Cannot send an invitation to yourself");
+    if (sender === receiver) {
+        throw new ConflictException('Cannot send an invitation to yourself');
     }
 
     const data = req.body as TeacherInvitationData;
diff --git a/backend/src/interfaces/user.ts b/backend/src/interfaces/user.ts
index 88252a1e..3084c494 100644
--- a/backend/src/interfaces/user.ts
+++ b/backend/src/interfaces/user.ts
@@ -10,7 +10,7 @@ export function mapToUserDTO(user: User): UserDTO {
     };
 }
 
-export function mapToUsername(user: {username: string}): string {
+export function mapToUsername(user: { username: string }): string {
     return user.username;
 }
 
diff --git a/backend/src/middleware/auth/auth.ts b/backend/src/middleware/auth/auth.ts
index 158e2c28..24be4825 100644
--- a/backend/src/middleware/auth/auth.ts
+++ b/backend/src/middleware/auth/auth.ts
@@ -1,11 +1,11 @@
-import {envVars, getEnvVar} from '../../util/envVars.js';
-import {expressjwt} from 'express-jwt';
+import { envVars, getEnvVar } from '../../util/envVars.js';
+import { expressjwt } from 'express-jwt';
 import * as jwt from 'jsonwebtoken';
-import {JwtPayload} from 'jsonwebtoken';
+import { JwtPayload } from 'jsonwebtoken';
 import jwksClient from 'jwks-rsa';
 import * as express from 'express';
-import {AuthenticatedRequest} from './authenticated-request.js';
-import {AuthenticationInfo} from './authentication-info.js';
+import { AuthenticatedRequest } from './authenticated-request.js';
+import { AuthenticationInfo } from './authentication-info.js';
 import { UnauthorizedException } from '../../exceptions/unauthorized-exception.js';
 
 const JWKS_CACHE = true;
diff --git a/backend/src/middleware/auth/authenticated-request.d.ts b/backend/src/middleware/auth/authenticated-request.d.ts
index c0049dc7..af7630af 100644
--- a/backend/src/middleware/auth/authenticated-request.d.ts
+++ b/backend/src/middleware/auth/authenticated-request.d.ts
@@ -1,7 +1,7 @@
 import { Request } from 'express';
 import { JwtPayload } from 'jsonwebtoken';
 import { AuthenticationInfo } from './authentication-info.js';
-import * as core from "express-serve-static-core";
+import * as core from 'express-serve-static-core';
 
 export interface AuthenticatedRequest<
     P = core.ParamsDictionary,
@@ -9,7 +9,7 @@ export interface AuthenticatedRequest<
     ReqBody = unknown,
     ReqQuery = core.Query,
     Locals extends Record<string, unknown> = Record<string, unknown>,
-> extends Request<P,ResBody,ReqBody,ReqQuery,Locals> {
+> extends Request<P, ResBody, ReqBody, ReqQuery, Locals> {
     // Properties are optional since the user is not necessarily authenticated.
     jwtPayload?: JwtPayload;
     auth?: AuthenticationInfo;
diff --git a/backend/src/middleware/auth/checks/assignment-auth-checks.ts b/backend/src/middleware/auth/checks/assignment-auth-checks.ts
index 070df4a0..8328dec0 100644
--- a/backend/src/middleware/auth/checks/assignment-auth-checks.ts
+++ b/backend/src/middleware/auth/checks/assignment-auth-checks.ts
@@ -1,7 +1,7 @@
-import {authorize} from "./auth-checks";
-import {fetchClass} from "../../../services/classes";
-import {fetchAllGroups} from "../../../services/groups";
-import {mapToUsername} from "../../../interfaces/user";
+import { authorize } from './auth-checks';
+import { fetchClass } from '../../../services/classes';
+import { fetchAllGroups } from '../../../services/groups';
+import { mapToUsername } from '../../../interfaces/user';
 
 /**
  * Expects the path to contain the path parameters 'classId' and 'id' (meaning the ID of the assignment).
@@ -9,15 +9,12 @@ import {mapToUsername} from "../../../interfaces/user";
  * - either teachers of the class the assignment was posted in,
  * - or students in a group of the assignment.
  */
-export const onlyAllowIfHasAccessToAssignment = authorize(
-    async (auth, req) => {
-        const { classid: classId, id: assignmentId } = req.params as { classid: string, id: number };
-        if (auth.accountType === "teacher") {
-            const clazz = await fetchClass(classId);
-            return clazz.teachers.map(mapToUsername).includes(auth.username);
-        } 
-            const groups = await fetchAllGroups(classId, assignmentId);
-            return groups.some(group => group.members.map((member) => member.username).includes(auth.username) );
-        
+export const onlyAllowIfHasAccessToAssignment = authorize(async (auth, req) => {
+    const { classid: classId, id: assignmentId } = req.params as { classid: string; id: number };
+    if (auth.accountType === 'teacher') {
+        const clazz = await fetchClass(classId);
+        return clazz.teachers.map(mapToUsername).includes(auth.username);
     }
-);
+    const groups = await fetchAllGroups(classId, assignmentId);
+    return groups.some((group) => group.members.map((member) => member.username).includes(auth.username));
+});
diff --git a/backend/src/middleware/auth/checks/auth-checks.ts b/backend/src/middleware/auth/checks/auth-checks.ts
index d14e8dee..a4a75db5 100644
--- a/backend/src/middleware/auth/checks/auth-checks.ts
+++ b/backend/src/middleware/auth/checks/auth-checks.ts
@@ -1,9 +1,9 @@
-import {AuthenticationInfo} from "../authentication-info";
-import {AuthenticatedRequest} from "../authenticated-request";
-import * as express from "express";
-import {UnauthorizedException} from "../../../exceptions/unauthorized-exception";
-import {ForbiddenException} from "../../../exceptions/forbidden-exception";
-import {RequestHandler} from "express";
+import { AuthenticationInfo } from '../authentication-info';
+import { AuthenticatedRequest } from '../authenticated-request';
+import * as express from 'express';
+import { UnauthorizedException } from '../../../exceptions/unauthorized-exception';
+import { ForbiddenException } from '../../../exceptions/forbidden-exception';
+import { RequestHandler } from 'express';
 
 /**
  * Middleware which rejects unauthenticated users (with HTTP 401) and authenticated users which do not fulfill
@@ -11,13 +11,17 @@ import {RequestHandler} from "express";
  * @param accessCondition Predicate over the current AuthenticationInfo. Access is only granted when this evaluates
  *                        to true.
  */
-export function authorize<P,ResBody,ReqBody,ReqQuery,Locals extends Record<string, unknown>>(
-    accessCondition: (auth: AuthenticationInfo, req: AuthenticatedRequest<P,ResBody,ReqBody,ReqQuery,Locals>) => boolean | Promise<boolean>
-): RequestHandler<P,ResBody,ReqBody,ReqQuery,Locals> {
-    return async (req: AuthenticatedRequest<P,ResBody,ReqBody,ReqQuery,Locals>, _res: express.Response, next: express.NextFunction): Promise<void> => {
+export function authorize<P, ResBody, ReqBody, ReqQuery, Locals extends Record<string, unknown>>(
+    accessCondition: (auth: AuthenticationInfo, req: AuthenticatedRequest<P, ResBody, ReqBody, ReqQuery, Locals>) => boolean | Promise<boolean>
+): RequestHandler<P, ResBody, ReqBody, ReqQuery, Locals> {
+    return async (
+        req: AuthenticatedRequest<P, ResBody, ReqBody, ReqQuery, Locals>,
+        _res: express.Response,
+        next: express.NextFunction
+    ): Promise<void> => {
         if (!req.auth) {
             throw new UnauthorizedException();
-        } else if (!await accessCondition(req.auth, req)) {
+        } else if (!(await accessCondition(req.auth, req))) {
             throw new ForbiddenException();
         } else {
             next();
diff --git a/backend/src/middleware/auth/checks/class-auth-checks.ts b/backend/src/middleware/auth/checks/class-auth-checks.ts
index 603142be..6aae97b3 100644
--- a/backend/src/middleware/auth/checks/class-auth-checks.ts
+++ b/backend/src/middleware/auth/checks/class-auth-checks.ts
@@ -1,8 +1,8 @@
-import {authorize} from "./auth-checks";
-import {AuthenticationInfo} from "../authentication-info";
-import {AuthenticatedRequest} from "../authenticated-request";
-import {fetchClass} from "../../../services/classes";
-import {mapToUsername} from "../../../interfaces/user";
+import { authorize } from './auth-checks';
+import { AuthenticationInfo } from '../authentication-info';
+import { AuthenticatedRequest } from '../authenticated-request';
+import { fetchClass } from '../../../services/classes';
+import { mapToUsername } from '../../../interfaces/user';
 
 async function teaches(teacherUsername: string, classId: string): Promise<boolean> {
     const clazz = await fetchClass(classId);
@@ -14,53 +14,45 @@ async function teaches(teacherUsername: string, classId: string): Promise<boolea
  * Only allows requests whose username parameter is equal to the username of the user who is logged in and requests
  * whose classId parameter references a class the logged-in user is a teacher of.
  */
-export const onlyAllowStudentHimselfAndTeachersOfClass = authorize(
-    async (auth: AuthenticationInfo, req: AuthenticatedRequest) => {
-        if (req.params.username === auth.username) {
-            return true;
-        } else if (auth.accountType === "teacher") {
-            return teaches(auth.username, req.params.classId);
-        }
-        return false;
-
+export const onlyAllowStudentHimselfAndTeachersOfClass = authorize(async (auth: AuthenticationInfo, req: AuthenticatedRequest) => {
+    if (req.params.username === auth.username) {
+        return true;
+    } else if (auth.accountType === 'teacher') {
+        return teaches(auth.username, req.params.classId);
     }
-);
+    return false;
+});
 
 /**
  * Only let the request pass through if its path parameter "username" is the username of the currently logged-in
  * teacher and the path parameter "classId" refers to a class the teacher teaches.
  */
 export const onlyAllowTeacherOfClass = authorize(
-    async (auth: AuthenticationInfo, req: AuthenticatedRequest) =>
-        req.params.username === auth.username && teaches(auth.username, req.params.classId),
+    async (auth: AuthenticationInfo, req: AuthenticatedRequest) => req.params.username === auth.username && teaches(auth.username, req.params.classId)
 );
 
 /**
  * Only let the request pass through if the class id in it refers to a class the current user is in (as a student
  * or teacher)
  */
-export const onlyAllowIfInClass = authorize(
-    async (auth: AuthenticationInfo, req: AuthenticatedRequest) => {
-        const classId = req.params.classId ?? req.params.classid ?? req.params.id;
-        const clazz = await fetchClass(classId);
-        if (auth.accountType === "teacher") {
-            return clazz.teachers.map(mapToUsername).includes(auth.username);
-        }
-        return clazz.students.map(mapToUsername).includes(auth.username);
+export const onlyAllowIfInClass = authorize(async (auth: AuthenticationInfo, req: AuthenticatedRequest) => {
+    const classId = req.params.classId ?? req.params.classid ?? req.params.id;
+    const clazz = await fetchClass(classId);
+    if (auth.accountType === 'teacher') {
+        return clazz.teachers.map(mapToUsername).includes(auth.username);
     }
-);
+    return clazz.students.map(mapToUsername).includes(auth.username);
+});
 
 /**
  * Only allows the request to pass if the 'class' property in its body is a class the current user is a member of.
  */
-export const onlyAllowOwnClassInBody = authorize(
-    async (auth, req) => {
-        const classId = (req.body as {class: string})?.class;
-        const clazz = await fetchClass(classId);
+export const onlyAllowOwnClassInBody = authorize(async (auth, req) => {
+    const classId = (req.body as { class: string })?.class;
+    const clazz = await fetchClass(classId);
 
-        if (auth.accountType === "teacher") {
-            return clazz.teachers.map(mapToUsername).includes(auth.username);
-        }
-        return clazz.students.map(mapToUsername).includes(auth.username);
+    if (auth.accountType === 'teacher') {
+        return clazz.teachers.map(mapToUsername).includes(auth.username);
     }
-);
+    return clazz.students.map(mapToUsername).includes(auth.username);
+});
diff --git a/backend/src/middleware/auth/checks/group-auth-checker.ts b/backend/src/middleware/auth/checks/group-auth-checker.ts
index 643a3713..bebda954 100644
--- a/backend/src/middleware/auth/checks/group-auth-checker.ts
+++ b/backend/src/middleware/auth/checks/group-auth-checker.ts
@@ -1,7 +1,7 @@
-import {authorize} from "./auth-checks";
-import {fetchClass} from "../../../services/classes";
-import {fetchGroup} from "../../../services/groups";
-import {mapToUsername} from "../../../interfaces/user";
+import { authorize } from './auth-checks';
+import { fetchClass } from '../../../services/classes';
+import { fetchGroup } from '../../../services/groups';
+import { mapToUsername } from '../../../interfaces/user';
 
 /**
  * Expects the path to contain the path parameters 'classid', 'assignmentid' and 'groupid'.
@@ -9,17 +9,17 @@ import {mapToUsername} from "../../../interfaces/user";
  * - either teachers of the class the assignment for the group was posted in,
  * - or students in the group
  */
-export const onlyAllowIfHasAccessToGroup = authorize(
-    async (auth, req) => {
-        const { classid: classId, assignmentid: assignmentId, groupid: groupId } =
-            req.params as { classid: string, assignmentid: number, groupid: number };
+export const onlyAllowIfHasAccessToGroup = authorize(async (auth, req) => {
+    const {
+        classid: classId,
+        assignmentid: assignmentId,
+        groupid: groupId,
+    } = req.params as { classid: string; assignmentid: number; groupid: number };
 
-        if (auth.accountType === "teacher") {
-            const clazz = await fetchClass(classId);
-            return clazz.teachers.map(mapToUsername).includes(auth.username);
-        }  // User is student
-            const group = await fetchGroup(classId, assignmentId, groupId);
-            return group.members.map(mapToUsername).includes(auth.username);
-        
-    }
-);
+    if (auth.accountType === 'teacher') {
+        const clazz = await fetchClass(classId);
+        return clazz.teachers.map(mapToUsername).includes(auth.username);
+    } // User is student
+    const group = await fetchGroup(classId, assignmentId, groupId);
+    return group.members.map(mapToUsername).includes(auth.username);
+});
diff --git a/backend/src/middleware/auth/checks/learning-content-auth-checks.ts b/backend/src/middleware/auth/checks/learning-content-auth-checks.ts
index a13cd038..c0b34c52 100644
--- a/backend/src/middleware/auth/checks/learning-content-auth-checks.ts
+++ b/backend/src/middleware/auth/checks/learning-content-auth-checks.ts
@@ -1,6 +1,6 @@
-import {authorize} from "./auth-checks";
-import {AuthenticationInfo} from "../authentication-info";
-import {AuthenticatedRequest} from "../authenticated-request";
+import { authorize } from './auth-checks';
+import { AuthenticationInfo } from '../authentication-info';
+import { AuthenticatedRequest } from '../authenticated-request';
 
 /**
  * Only allows requests whose learning path personalization query parameters ('forGroup' / 'assignmentNo' / 'classId')
@@ -9,15 +9,12 @@ import {AuthenticatedRequest} from "../authenticated-request";
  * - or set to a group the user is in,
  * - or set to anything if the user is a teacher.
  */
-export const onlyAllowPersonalizationForOwnGroup = authorize(
-    async (auth: AuthenticationInfo, req: AuthenticatedRequest) => {
-        const {forGroup, assignmentNo, classId} = req.params;
-        if (auth.accountType === "student" && forGroup && assignmentNo && classId) {
-            // TODO: groupNumber? 
-            // Const group = await fetchGroup(Number(classId), Number(assignmentNo), )
-            return false;
-        } 
-            return true;
-        
+export const onlyAllowPersonalizationForOwnGroup = authorize(async (auth: AuthenticationInfo, req: AuthenticatedRequest) => {
+    const { forGroup, assignmentNo, classId } = req.params;
+    if (auth.accountType === 'student' && forGroup && assignmentNo && classId) {
+        // TODO: groupNumber?
+        // Const group = await fetchGroup(Number(classId), Number(assignmentNo), )
+        return false;
     }
-);
+    return true;
+});
diff --git a/backend/src/middleware/auth/checks/question-checks.ts b/backend/src/middleware/auth/checks/question-checks.ts
index 38b1f0ef..c0a4329f 100644
--- a/backend/src/middleware/auth/checks/question-checks.ts
+++ b/backend/src/middleware/auth/checks/question-checks.ts
@@ -1,72 +1,65 @@
-import {authorize} from "./auth-checks";
-import {AuthenticationInfo} from "../authentication-info";
-import {AuthenticatedRequest} from "../authenticated-request";
-import {requireFields} from "../../../controllers/error-helper";
-import {getLearningObjectId, getQuestionId} from "../../../controllers/questions";
-import {fetchQuestion} from "../../../services/questions";
-import {FALLBACK_SEQ_NUM} from "../../../config";
-import {fetchAnswer} from "../../../services/answers";
-import {mapToUsername} from "../../../interfaces/user";
+import { authorize } from './auth-checks';
+import { AuthenticationInfo } from '../authentication-info';
+import { AuthenticatedRequest } from '../authenticated-request';
+import { requireFields } from '../../../controllers/error-helper';
+import { getLearningObjectId, getQuestionId } from '../../../controllers/questions';
+import { fetchQuestion } from '../../../services/questions';
+import { FALLBACK_SEQ_NUM } from '../../../config';
+import { fetchAnswer } from '../../../services/answers';
+import { mapToUsername } from '../../../interfaces/user';
 
 export const onlyAllowAuthor = authorize(
     (auth: AuthenticationInfo, req: AuthenticatedRequest) => (req.body as { author: string }).author === auth.username
 );
 
-export const onlyAllowAuthorRequest = authorize(
-    async (auth: AuthenticationInfo, req: AuthenticatedRequest) => {
-        const hruid = req.params.hruid;
-        const version = req.params.version;
-        const language = req.query.lang as string;
-        const seq = req.params.seq;
-        requireFields({ hruid });
+export const onlyAllowAuthorRequest = authorize(async (auth: AuthenticationInfo, req: AuthenticatedRequest) => {
+    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 learningObjectId = getLearningObjectId(hruid, version, language);
+    const questionId = getQuestionId(learningObjectId, seq);
 
-        const question = await fetchQuestion(questionId);
+    const question = await fetchQuestion(questionId);
 
-        return question.author.username === auth.username;
-    }
-);
+    return question.author.username === auth.username;
+});
 
-export const onlyAllowAuthorRequestAnswer = authorize(
-    async (auth: AuthenticationInfo, req: AuthenticatedRequest) => {
-        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 });
+export const onlyAllowAuthorRequestAnswer = authorize(async (auth: AuthenticationInfo, req: AuthenticatedRequest) => {
+    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 learningObjectId = getLearningObjectId(hruid, version, language);
+    const questionId = getQuestionId(learningObjectId, seq);
 
-        const sequenceNumber = Number(seqAnswer) || FALLBACK_SEQ_NUM;
-        const answer = await fetchAnswer(questionId, sequenceNumber);
+    const sequenceNumber = Number(seqAnswer) || FALLBACK_SEQ_NUM;
+    const answer = await fetchAnswer(questionId, sequenceNumber);
 
-        return answer.author.username === auth.username;
-    }
-);
+    return answer.author.username === auth.username;
+});
 
-export const onlyAllowIfHasAccessToQuestion = authorize(
-    async (auth: AuthenticationInfo, req: AuthenticatedRequest) => {
-        const hruid = req.params.hruid;
-        const version = req.params.version;
-        const language = req.query.lang as string;
-        const seq = req.params.seq;
-        requireFields({ hruid });
+export const onlyAllowIfHasAccessToQuestion = authorize(async (auth: AuthenticationInfo, req: AuthenticatedRequest) => {
+    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 learningObjectId = getLearningObjectId(hruid, version, language);
+    const questionId = getQuestionId(learningObjectId, seq);
 
-        const question = await fetchQuestion(questionId);
-        const group = question.inGroup;
+    const question = await fetchQuestion(questionId);
+    const group = question.inGroup;
 
-        if (auth.accountType === "teacher") {
-            const cls = group.assignment.within; // TODO check if contains full objects
-            return cls.teachers.map(mapToUsername).includes(auth.username);
-        }  // User is student
-            return group.members.map(mapToUsername).includes(auth.username);
-        
-    }
-);
+    if (auth.accountType === 'teacher') {
+        const cls = group.assignment.within; // TODO check if contains full objects
+        return cls.teachers.map(mapToUsername).includes(auth.username);
+    } // User is student
+    return group.members.map(mapToUsername).includes(auth.username);
+});
diff --git a/backend/src/middleware/auth/checks/submission-checks.ts b/backend/src/middleware/auth/checks/submission-checks.ts
index 78087fa9..87171584 100644
--- a/backend/src/middleware/auth/checks/submission-checks.ts
+++ b/backend/src/middleware/auth/checks/submission-checks.ts
@@ -1,29 +1,27 @@
-import { languageMap } from "dwengo-1-common/util/language";
-import { LearningObjectIdentifier } from "../../../entities/content/learning-object-identifier";
-import { fetchSubmission } from "../../../services/submissions";
-import { AuthenticatedRequest } from "../authenticated-request";
-import { AuthenticationInfo } from "../authentication-info";
-import { authorize } from "./auth-checks";
-import { FALLBACK_LANG } from "../../../config";
-import { mapToUsername } from "../../../interfaces/user";
+import { languageMap } from 'dwengo-1-common/util/language';
+import { LearningObjectIdentifier } from '../../../entities/content/learning-object-identifier';
+import { fetchSubmission } from '../../../services/submissions';
+import { AuthenticatedRequest } from '../authenticated-request';
+import { AuthenticationInfo } from '../authentication-info';
+import { authorize } from './auth-checks';
+import { FALLBACK_LANG } from '../../../config';
+import { mapToUsername } from '../../../interfaces/user';
 
 export const onlyAllowSubmitter = authorize(
     (auth: AuthenticationInfo, req: AuthenticatedRequest) => (req.body as { submitter: string }).submitter === auth.username
 );
 
-export const onlyAllowIfHasAccessToSubmission = authorize(
-    async (auth: AuthenticationInfo, req: AuthenticatedRequest) => {
-        const { hruid: lohruid, id: submissionNumber } = req.params;
-        const { language: lang, version: version } = req.query;
+export const onlyAllowIfHasAccessToSubmission = authorize(async (auth: AuthenticationInfo, req: AuthenticatedRequest) => {
+    const { hruid: lohruid, id: submissionNumber } = req.params;
+    const { language: lang, version: version } = req.query;
 
-        const loId = new LearningObjectIdentifier(lohruid,  languageMap[lang as string] ?? FALLBACK_LANG, Number(version))
-        const submission = await fetchSubmission(loId, Number(submissionNumber));
+    const loId = new LearningObjectIdentifier(lohruid, languageMap[lang as string] ?? FALLBACK_LANG, Number(version));
+    const submission = await fetchSubmission(loId, Number(submissionNumber));
 
-        if (auth.accountType === "teacher") {
-            // Dit kan niet werken om dat al deze objecten niet gepopulate zijn. 
-            return submission.onBehalfOf.assignment.within.teachers.map(mapToUsername).includes(auth.username);
-        } 
-
-        return submission.onBehalfOf.members.map(mapToUsername).includes(auth.username);
+    if (auth.accountType === 'teacher') {
+        // Dit kan niet werken om dat al deze objecten niet gepopulate zijn.
+        return submission.onBehalfOf.assignment.within.teachers.map(mapToUsername).includes(auth.username);
     }
-)
\ No newline at end of file
+
+    return submission.onBehalfOf.members.map(mapToUsername).includes(auth.username);
+});
diff --git a/backend/src/middleware/auth/checks/teacher-invitation-checks.ts b/backend/src/middleware/auth/checks/teacher-invitation-checks.ts
index 27d0cab2..5f38eaf1 100644
--- a/backend/src/middleware/auth/checks/teacher-invitation-checks.ts
+++ b/backend/src/middleware/auth/checks/teacher-invitation-checks.ts
@@ -1,23 +1,17 @@
-import {authorize} from "./auth-checks";
-import {AuthenticationInfo} from "../authentication-info";
-import {AuthenticatedRequest} from "../authenticated-request";
+import { authorize } from './auth-checks';
+import { AuthenticationInfo } from '../authentication-info';
+import { AuthenticatedRequest } from '../authenticated-request';
 
 export const onlyAllowSenderOrReceiver = authorize(
-    (auth: AuthenticationInfo, req: AuthenticatedRequest) =>
-        req.params.sender === auth.username || req.params.receiver === auth.username
+    (auth: AuthenticationInfo, req: AuthenticatedRequest) => req.params.sender === auth.username || req.params.receiver === auth.username
 );
 
-export const onlyAllowSender = authorize(
-    (auth: AuthenticationInfo, req: AuthenticatedRequest) =>
-        req.params.sender === auth.username
-);
+export const onlyAllowSender = authorize((auth: AuthenticationInfo, req: AuthenticatedRequest) => req.params.sender === auth.username);
 
 export const onlyAllowSenderBody = authorize(
-    (auth: AuthenticationInfo, req: AuthenticatedRequest) =>
-        (req.body as { sender: string }).sender === auth.username
+    (auth: AuthenticationInfo, req: AuthenticatedRequest) => (req.body as { sender: string }).sender === auth.username
 );
 
 export const onlyAllowReceiverBody = authorize(
-    (auth: AuthenticationInfo, req: AuthenticatedRequest) =>
-        (req.body as { receiver: string }).receiver === auth.username
+    (auth: AuthenticationInfo, req: AuthenticatedRequest) => (req.body as { receiver: string }).receiver === auth.username
 );
diff --git a/backend/src/middleware/auth/checks/user-auth-checks.ts b/backend/src/middleware/auth/checks/user-auth-checks.ts
index 10814eb8..bbe4c7f2 100644
--- a/backend/src/middleware/auth/checks/user-auth-checks.ts
+++ b/backend/src/middleware/auth/checks/user-auth-checks.ts
@@ -1,10 +1,8 @@
-import {authorize} from "./auth-checks";
-import {AuthenticationInfo} from "../authentication-info";
-import {AuthenticatedRequest} from "../authenticated-request";
+import { authorize } from './auth-checks';
+import { AuthenticationInfo } from '../authentication-info';
+import { AuthenticatedRequest } from '../authenticated-request';
 
 /**
  * Only allow the user whose username is in the path parameter "username" to access the endpoint.
  */
-export const onlyAllowUserHimself = authorize(
-    (auth: AuthenticationInfo, req: AuthenticatedRequest) => req.params.username === auth.username
-);
+export const onlyAllowUserHimself = authorize((auth: AuthenticationInfo, req: AuthenticatedRequest) => req.params.username === auth.username);
diff --git a/backend/src/routes/answers.ts b/backend/src/routes/answers.ts
index a5ee6278..6e76a543 100644
--- a/backend/src/routes/answers.ts
+++ b/backend/src/routes/answers.ts
@@ -1,12 +1,7 @@
 import express from 'express';
 import { createAnswerHandler, deleteAnswerHandler, getAnswerHandler, getAllAnswersHandler, updateAnswerHandler } from '../controllers/answers.js';
-import {adminOnly, teachersOnly} from "../middleware/auth/checks/auth-checks";
-import {
-    onlyAllowAuthor,
-    onlyAllowAuthorRequestAnswer,
-    onlyAllowIfHasAccessToQuestion
-} from "../middleware/auth/checks/question-checks";
-
+import { adminOnly, teachersOnly } from '../middleware/auth/checks/auth-checks';
+import { onlyAllowAuthor, onlyAllowAuthorRequestAnswer, onlyAllowIfHasAccessToQuestion } from '../middleware/auth/checks/question-checks';
 
 const router = express.Router({ mergeParams: true });
 
diff --git a/backend/src/routes/assignments.ts b/backend/src/routes/assignments.ts
index 7b2d66fa..2a38748b 100644
--- a/backend/src/routes/assignments.ts
+++ b/backend/src/routes/assignments.ts
@@ -8,9 +8,9 @@ import {
     putAssignmentHandler,
 } from '../controllers/assignments.js';
 import groupRouter from './groups.js';
-import {teachersOnly} from "../middleware/auth/checks/auth-checks";
-import {onlyAllowIfInClass} from "../middleware/auth/checks/class-auth-checks";
-import {onlyAllowIfHasAccessToAssignment} from "../middleware/auth/checks/assignment-auth-checks";
+import { teachersOnly } from '../middleware/auth/checks/auth-checks';
+import { onlyAllowIfInClass } from '../middleware/auth/checks/class-auth-checks';
+import { onlyAllowIfHasAccessToAssignment } from '../middleware/auth/checks/assignment-auth-checks';
 
 const router = express.Router({ mergeParams: true });
 
diff --git a/backend/src/routes/classes.ts b/backend/src/routes/classes.ts
index 9cf20ec0..9889151d 100644
--- a/backend/src/routes/classes.ts
+++ b/backend/src/routes/classes.ts
@@ -14,8 +14,8 @@ import {
     putClassHandler,
 } from '../controllers/classes.js';
 import assignmentRouter from './assignments.js';
-import {adminOnly, teachersOnly} from "../middleware/auth/checks/auth-checks";
-import {onlyAllowIfInClass} from "../middleware/auth/checks/class-auth-checks";
+import { adminOnly, teachersOnly } from '../middleware/auth/checks/auth-checks';
+import { onlyAllowIfInClass } from '../middleware/auth/checks/class-auth-checks';
 
 const router = express.Router();
 
diff --git a/backend/src/routes/groups.ts b/backend/src/routes/groups.ts
index 5d3d8ed0..cb92e7c2 100644
--- a/backend/src/routes/groups.ts
+++ b/backend/src/routes/groups.ts
@@ -7,9 +7,9 @@ import {
     getGroupSubmissionsHandler,
     putGroupHandler,
 } from '../controllers/groups.js';
-import {onlyAllowIfHasAccessToGroup} from "../middleware/auth/checks/group-auth-checker";
-import {teachersOnly} from "../middleware/auth/checks/auth-checks";
-import {onlyAllowIfHasAccessToAssignment} from "../middleware/auth/checks/assignment-auth-checks";
+import { onlyAllowIfHasAccessToGroup } from '../middleware/auth/checks/group-auth-checker';
+import { teachersOnly } from '../middleware/auth/checks/auth-checks';
+import { onlyAllowIfHasAccessToAssignment } from '../middleware/auth/checks/assignment-auth-checks';
 
 const router = express.Router({ mergeParams: true });
 
diff --git a/backend/src/routes/learning-objects.ts b/backend/src/routes/learning-objects.ts
index fb65d9cd..fa438a57 100644
--- a/backend/src/routes/learning-objects.ts
+++ b/backend/src/routes/learning-objects.ts
@@ -3,7 +3,7 @@ import { getAllLearningObjects, getAttachment, getLearningObject, getLearningObj
 
 import submissionRoutes from './submissions.js';
 import questionRoutes from './questions.js';
-import {authenticatedOnly} from "../middleware/auth/checks/auth-checks";
+import { authenticatedOnly } from '../middleware/auth/checks/auth-checks';
 
 const router = express.Router();
 
diff --git a/backend/src/routes/learning-paths.ts b/backend/src/routes/learning-paths.ts
index ad079551..ee3c4955 100644
--- a/backend/src/routes/learning-paths.ts
+++ b/backend/src/routes/learning-paths.ts
@@ -1,6 +1,6 @@
 import express from 'express';
 import { getLearningPaths } from '../controllers/learning-paths.js';
-import {authenticatedOnly} from "../middleware/auth/checks/auth-checks";
+import { authenticatedOnly } from '../middleware/auth/checks/auth-checks';
 
 const router = express.Router();
 
diff --git a/backend/src/routes/questions.ts b/backend/src/routes/questions.ts
index bffcbe9e..a15c1d0a 100644
--- a/backend/src/routes/questions.ts
+++ b/backend/src/routes/questions.ts
@@ -1,13 +1,9 @@
 import express from 'express';
 import { createQuestionHandler, deleteQuestionHandler, getAllQuestionsHandler, getQuestionHandler } from '../controllers/questions.js';
 import answerRoutes from './answers.js';
-import {adminOnly, studentsOnly} from "../middleware/auth/checks/auth-checks";
-import {updateAnswerHandler} from "../controllers/answers";
-import {
-    onlyAllowAuthor,
-    onlyAllowAuthorRequest,
-    onlyAllowIfHasAccessToQuestion
-} from "../middleware/auth/checks/question-checks";
+import { adminOnly, studentsOnly } from '../middleware/auth/checks/auth-checks';
+import { updateAnswerHandler } from '../controllers/answers';
+import { onlyAllowAuthor, onlyAllowAuthorRequest, onlyAllowIfHasAccessToQuestion } from '../middleware/auth/checks/question-checks';
 
 const router = express.Router({ mergeParams: true });
 
@@ -23,7 +19,7 @@ router.get('/:seq', onlyAllowIfHasAccessToQuestion, getQuestionHandler);
 
 router.delete('/:seq', studentsOnly, onlyAllowAuthorRequest, deleteQuestionHandler);
 
-router.put("/:seq", studentsOnly, onlyAllowAuthorRequest, updateAnswerHandler);
+router.put('/:seq', studentsOnly, onlyAllowAuthorRequest, updateAnswerHandler);
 
 router.use('/:seq/answers', answerRoutes);
 
diff --git a/backend/src/routes/student-join-requests.ts b/backend/src/routes/student-join-requests.ts
index 66a6c75e..f467f346 100644
--- a/backend/src/routes/student-join-requests.ts
+++ b/backend/src/routes/student-join-requests.ts
@@ -5,8 +5,8 @@ import {
     getStudentRequestHandler,
     getStudentRequestsHandler,
 } from '../controllers/students.js';
-import {onlyAllowUserHimself} from "../middleware/auth/checks/user-auth-checks";
-import {onlyAllowStudentHimselfAndTeachersOfClass} from "../middleware/auth/checks/class-auth-checks";
+import { onlyAllowUserHimself } from '../middleware/auth/checks/user-auth-checks';
+import { onlyAllowStudentHimselfAndTeachersOfClass } from '../middleware/auth/checks/class-auth-checks';
 
 // Under /:username/joinRequests/
 
diff --git a/backend/src/routes/students.ts b/backend/src/routes/students.ts
index 04d260b4..e0634219 100644
--- a/backend/src/routes/students.ts
+++ b/backend/src/routes/students.ts
@@ -11,8 +11,8 @@ import {
     getStudentSubmissionsHandler,
 } from '../controllers/students.js';
 import joinRequestRouter from './student-join-requests.js';
-import {onlyAllowUserHimself} from "../middleware/auth/checks/user-auth-checks";
-import {adminOnly} from "../middleware/auth/checks/auth-checks";
+import { onlyAllowUserHimself } from '../middleware/auth/checks/user-auth-checks';
+import { adminOnly } from '../middleware/auth/checks/auth-checks';
 
 const router = express.Router();
 
diff --git a/backend/src/routes/teacher-invitations.ts b/backend/src/routes/teacher-invitations.ts
index fe0b924f..d9c98e5f 100644
--- a/backend/src/routes/teacher-invitations.ts
+++ b/backend/src/routes/teacher-invitations.ts
@@ -6,18 +6,19 @@ import {
     getInvitationHandler,
     updateInvitationHandler,
 } from '../controllers/teacher-invitations';
-import {onlyAllowUserHimself} from "../middleware/auth/checks/user-auth-checks";
+import { onlyAllowUserHimself } from '../middleware/auth/checks/user-auth-checks';
 import {
-    onlyAllowReceiverBody, onlyAllowSender,
+    onlyAllowReceiverBody,
+    onlyAllowSender,
     onlyAllowSenderBody,
-    onlyAllowSenderOrReceiver
-} from "../middleware/auth/checks/teacher-invitation-checks";
+    onlyAllowSenderOrReceiver,
+} from '../middleware/auth/checks/teacher-invitation-checks';
 
 const router = express.Router({ mergeParams: true });
 
 router.get('/:username', onlyAllowUserHimself, getAllInvitationsHandler);
 
-router.get('/:sender/:receiver/:classId', onlyAllowSenderOrReceiver ,getInvitationHandler);
+router.get('/:sender/:receiver/:classId', onlyAllowSenderOrReceiver, getInvitationHandler);
 
 router.post('/', onlyAllowSenderBody, createInvitationHandler);
 
diff --git a/backend/src/routes/teachers.ts b/backend/src/routes/teachers.ts
index 776b9951..edd06118 100644
--- a/backend/src/routes/teachers.ts
+++ b/backend/src/routes/teachers.ts
@@ -12,9 +12,9 @@ import {
 } from '../controllers/teachers.js';
 import invitationRouter from './teacher-invitations.js';
 
-import {adminOnly} from "../middleware/auth/checks/auth-checks";
-import {onlyAllowUserHimself} from "../middleware/auth/checks/user-auth-checks";
-import {onlyAllowTeacherOfClass} from "../middleware/auth/checks/class-auth-checks";
+import { adminOnly } from '../middleware/auth/checks/auth-checks';
+import { onlyAllowUserHimself } from '../middleware/auth/checks/user-auth-checks';
+import { onlyAllowTeacherOfClass } from '../middleware/auth/checks/class-auth-checks';
 const router = express.Router();
 
 // Root endpoint used to search objects
diff --git a/backend/src/routes/themes.ts b/backend/src/routes/themes.ts
index 089c5d46..c5882a2a 100644
--- a/backend/src/routes/themes.ts
+++ b/backend/src/routes/themes.ts
@@ -1,6 +1,6 @@
 import express from 'express';
 import { getThemesHandler, getHruidsByThemeHandler } from '../controllers/themes.js';
-import {authenticatedOnly} from "../middleware/auth/checks/auth-checks";
+import { authenticatedOnly } from '../middleware/auth/checks/auth-checks';
 
 const router = express.Router();
 
diff --git a/backend/src/services/questions.ts b/backend/src/services/questions.ts
index 70400226..5894ad6f 100644
--- a/backend/src/services/questions.ts
+++ b/backend/src/services/questions.ts
@@ -12,7 +12,7 @@ import { AssignmentDTO } from '@dwengo-1/common/interfaces/assignment';
 import { fetchStudent } from './students.js';
 import { NotFoundException } from '../exceptions/not-found-exception.js';
 import { FALLBACK_VERSION_NUM } from '../config.js';
-import {ConflictException} from "../exceptions/conflict-exception";
+import { ConflictException } from '../exceptions/conflict-exception';
 
 export async function getQuestionsAboutLearningObjectInAssignment(
     loId: LearningObjectIdentifier,
@@ -91,12 +91,12 @@ export async function createQuestion(loId: LearningObjectIdentifier, questionDat
     const assignment = mapToAssignment(questionData.inGroup.assignment as AssignmentDTO, clazz!);
     const group = await getGroupRepository().findByAssignmentAndGroupNumber(assignment, questionData.inGroup.groupNumber);
 
-    if (!group){
-        throw new NotFoundException("Group with id and assignment not found");
+    if (!group) {
+        throw new NotFoundException('Group with id and assignment not found');
     }
 
-    if (! group.members.contains(author)) {
-        throw new ConflictException("Author is not part of this group");
+    if (!group.members.contains(author)) {
+        throw new ConflictException('Author is not part of this group');
     }
 
     const question = await questionRepository.createQuestion({
diff --git a/backend/src/services/students.ts b/backend/src/services/students.ts
index 09ba1643..de6a9254 100644
--- a/backend/src/services/students.ts
+++ b/backend/src/services/students.ts
@@ -25,7 +25,7 @@ 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';
-import {mapToUsername} from "../interfaces/user";
+import { mapToUsername } from '../interfaces/user';
 
 export async function getAllStudents(full: boolean): Promise<StudentDTO[] | string[]> {
     const studentRepository = getStudentRepository();
diff --git a/backend/src/services/teacher-invitations.ts b/backend/src/services/teacher-invitations.ts
index 6aec819b..0457496f 100644
--- a/backend/src/services/teacher-invitations.ts
+++ b/backend/src/services/teacher-invitations.ts
@@ -32,7 +32,7 @@ export async function createInvitation(data: TeacherInvitationData): Promise<Tea
         throw new ConflictException('The teacher sending the invite is not part of the class');
     }
 
-    if (cls.teachers.contains(receiver)){
+    if (cls.teachers.contains(receiver)) {
         throw new ConflictException('The teacher receiving the invite is already part of the class');
     }
 
diff --git a/backend/src/services/teachers.ts b/backend/src/services/teachers.ts
index 79072616..46336bd7 100644
--- a/backend/src/services/teachers.ts
+++ b/backend/src/services/teachers.ts
@@ -30,7 +30,7 @@ import { QuestionDTO, QuestionId } from '@dwengo-1/common/interfaces/question';
 import { ClassJoinRequestDTO } from '@dwengo-1/common/interfaces/class-join-request';
 import { ClassStatus } from '@dwengo-1/common/util/class-join-request';
 import { ConflictException } from '../exceptions/conflict-exception.js';
-import {mapToUsername} from "../interfaces/user";
+import { mapToUsername } from '../interfaces/user';
 
 export async function getAllTeachers(full: boolean): Promise<TeacherDTO[] | string[]> {
     const teacherRepository: TeacherRepository = getTeacherRepository();