diff --git a/backend/src/data/assignments/assignment-repository.ts b/backend/src/data/assignments/assignment-repository.ts
new file mode 100644
index 00000000..dcc2b45a
--- /dev/null
+++ b/backend/src/data/assignments/assignment-repository.ts
@@ -0,0 +1,15 @@
+import {DwengoEntityRepository} from "../dwengo-entity-repository";
+import {Assignment} from "../../entities/assignments/assignment.entity";
+import {Class} from "../../entities/classes/class.entity";
+
+export class AssignmentRepository extends DwengoEntityRepository<Assignment> {
+    public findByClassAndId(within: Class, id: number): Promise<Assignment | null> {
+        return this.findOne({within: within, id: id});
+    }
+    public findAllAssignmentsInClass(within: Class): Promise<Assignment[]> {
+        return this.findAll({where: {within: within}});
+    }
+    public deleteByClassAndId(within: Class, id: number): Promise<void> {
+        return this.deleteWhere({within: within, id: id});
+    }
+}
diff --git a/backend/src/data/assignments/group-repository.ts b/backend/src/data/assignments/group-repository.ts
new file mode 100644
index 00000000..c7856a62
--- /dev/null
+++ b/backend/src/data/assignments/group-repository.ts
@@ -0,0 +1,15 @@
+import {DwengoEntityRepository} from "../dwengo-entity-repository";
+import {Group} from "../../entities/assignments/group.entity";
+import {Assignment} from "../../entities/assignments/assignment.entity";
+
+export class GroupRepository extends DwengoEntityRepository<Group> {
+    public findByAssignmentAndGroupNumber(assignment: Assignment, groupNumber: number): Promise<Group | null> {
+        return this.findOne({assignment: assignment, groupNumber: groupNumber});
+    }
+    public findAllGroupsForAssignment(assignment: Assignment): Promise<Group[]> {
+        return this.findAll({where: {assignment: assignment}});
+    }
+    public deleteByAssignmentAndGroupNumber(assignment: Assignment, groupNumber: number) {
+        return this.deleteWhere({assignment: assignment, groupNumber: groupNumber});
+    }
+}
diff --git a/backend/src/data/assignments/submission-repository.ts b/backend/src/data/assignments/submission-repository.ts
new file mode 100644
index 00000000..90988578
--- /dev/null
+++ b/backend/src/data/assignments/submission-repository.ts
@@ -0,0 +1,34 @@
+import {DwengoEntityRepository} from "../dwengo-entity-repository";
+import {Group} from "../../entities/assignments/group.entity";
+import {Submission} from "../../entities/assignments/submission.entity";
+import {LearningObjectIdentifier} from "../../entities/content/learning-object-identifier";
+import {Student} from "../../entities/users/student.entity";
+
+export class SubmissionRepository extends DwengoEntityRepository<Submission> {
+    public findSubmissionByLearningObjectAndSubmissionNumber(loId: LearningObjectIdentifier, submissionNumber: number): Promise<Submission | null> {
+        return this.findOne({
+            learningObjectHruid: loId.hruid,
+            learningObjectLanguage: loId.language,
+            learningObjectVersion: loId.version,
+            submissionNumber: submissionNumber
+        });
+    }
+
+    public findMostRecentSubmissionForStudent(loId: LearningObjectIdentifier, submitter: Student): Promise<Submission | null> {
+        return this.findOne({
+            learningObjectHruid: loId.hruid,
+            learningObjectLanguage: loId.language,
+            learningObjectVersion: loId.version,
+            submitter: submitter,
+        }, {orderBy: {submissionNumber: "DESC"}})
+    }
+
+    public findMostRecentSubmissionForGroup(loId: LearningObjectIdentifier, group: Group): Promise<Submission | null> {
+        return this.findOne({
+            learningObjectHruid: loId.hruid,
+            learningObjectLanguage: loId.language,
+            learningObjectVersion: loId.version,
+            onBehalfOf: group,
+        }, {orderBy: {submissionNumber: "DESC"}})
+    }
+}
diff --git a/backend/src/entities/assigments/assignment.entity.ts b/backend/src/entities/assignments/assignment.entity.ts
similarity index 100%
rename from backend/src/entities/assigments/assignment.entity.ts
rename to backend/src/entities/assignments/assignment.entity.ts
diff --git a/backend/src/entities/assigments/group.entity.ts b/backend/src/entities/assignments/group.entity.ts
similarity index 100%
rename from backend/src/entities/assigments/group.entity.ts
rename to backend/src/entities/assignments/group.entity.ts
diff --git a/backend/src/entities/assigments/submission.entity.ts b/backend/src/entities/assignments/submission.entity.ts
similarity index 89%
rename from backend/src/entities/assigments/submission.entity.ts
rename to backend/src/entities/assignments/submission.entity.ts
index 8f833518..381ac503 100644
--- a/backend/src/entities/assigments/submission.entity.ts
+++ b/backend/src/entities/assignments/submission.entity.ts
@@ -4,7 +4,7 @@ import {Entity, Enum, ManyToOne, PrimaryKey, Property} from "@mikro-orm/core";
 import {Language} from "../content/language";
 
 @Entity()
-export class Submission<T> {
+export class Submission {
     @PrimaryKey({type: "string"})
     learningObjectHruid!: string;
 
@@ -14,7 +14,7 @@ export class Submission<T> {
     @PrimaryKey({type: "string"})
     learningObjectVersion: string = "1";
 
-    @Property({type: "integer"})
+    @PrimaryKey({type: "integer"})
     submissionNumber!: number;
 
     @ManyToOne({entity: () => Student})
@@ -27,5 +27,5 @@ export class Submission<T> {
     onBehalfOf?: Group;
 
     @Property({type: "json"})
-    content!: T;
+    content!: string;
 }
diff --git a/backend/src/entities/content/learning-object-identifier.ts b/backend/src/entities/content/learning-object-identifier.ts
new file mode 100644
index 00000000..544ce8ea
--- /dev/null
+++ b/backend/src/entities/content/learning-object-identifier.ts
@@ -0,0 +1,7 @@
+import {Language} from "./language";
+
+export class LearningObjectIdentifier {
+    constructor(public hruid: string, public language: Language, public version: string) {
+
+    }
+}
diff --git a/backend/src/entities/users/student.entity.ts b/backend/src/entities/users/student.entity.ts
index 36fb1812..14ba4ad5 100644
--- a/backend/src/entities/users/student.entity.ts
+++ b/backend/src/entities/users/student.entity.ts
@@ -1,7 +1,7 @@
 import {User} from "./user.entity";
 import {Collection, Entity, ManyToMany} from '@mikro-orm/core';
 import {Class} from "../classes/class.entity";
-import {Group} from "../assigments/group.entity";
+import {Group} from "../assignments/group.entity";
 import {StudentRepository} from "../../data/users/student-repository";
 
 @Entity({repository: () => StudentRepository})