diff --git a/backend/src/data/users/student-repository.ts b/backend/src/data/users/student-repository.ts
index 6835e430..d3be9081 100644
--- a/backend/src/data/users/student-repository.ts
+++ b/backend/src/data/users/student-repository.ts
@@ -1,4 +1,15 @@
 import { Student } from '../../entities/users/student.entity.js';
-import { UserRepository } from './user-repository.js';
+import { User } from '../../entities/users/user.entity.js';
+import { DwengoEntityRepository } from '../dwengo-entity-repository.js';
+// import { UserRepository } from './user-repository.js';
 
-export class StudentRepository extends UserRepository<Student> {}
+// export class StudentRepository extends UserRepository<Student> {}
+
+export class StudentRepository extends DwengoEntityRepository<Student> {
+    public findByUsername(username: string): Promise<Student | null> {
+        return this.findOne({ username: username });
+    }
+    public deleteByUsername(username: string): Promise<void> {
+        return this.deleteWhere({ username: username });
+    }
+}
\ No newline at end of file
diff --git a/backend/src/data/users/teacher-repository.ts b/backend/src/data/users/teacher-repository.ts
index 4c4f7687..23ba559e 100644
--- a/backend/src/data/users/teacher-repository.ts
+++ b/backend/src/data/users/teacher-repository.ts
@@ -1,4 +1,12 @@
 import { Teacher } from '../../entities/users/teacher.entity.js';
+import { DwengoEntityRepository } from '../dwengo-entity-repository.js';
 import { UserRepository } from './user-repository.js';
 
-export class TeacherRepository extends UserRepository<Teacher> {}
+export class TeacherRepository extends DwengoEntityRepository<Teacher> {
+    public findByUsername(username: string): Promise<Teacher | null> {
+        return this.findOne({ username: username });
+    }
+    public deleteByUsername(username: string): Promise<void> {
+        return this.deleteWhere({ username: username });
+    }
+}
\ No newline at end of file
diff --git a/backend/src/entities/assignments/assignment.entity.ts b/backend/src/entities/assignments/assignment.entity.ts
index ecb02b90..015dcdc5 100644
--- a/backend/src/entities/assignments/assignment.entity.ts
+++ b/backend/src/entities/assignments/assignment.entity.ts
@@ -1,4 +1,5 @@
 import {
+    Collection,
     Entity,
     Enum,
     ManyToOne,
@@ -50,5 +51,5 @@ export class Assignment {
         },
         mappedBy: 'assignment',
     })
-    groups!: Group[];
+    groups!: Collection<Group>;
 }
diff --git a/backend/src/entities/assignments/group.entity.ts b/backend/src/entities/assignments/group.entity.ts
index 0db4f6b0..446c0c0d 100644
--- a/backend/src/entities/assignments/group.entity.ts
+++ b/backend/src/entities/assignments/group.entity.ts
@@ -1,4 +1,4 @@
-import { Entity, ManyToMany, ManyToOne, PrimaryKey } from '@mikro-orm/core';
+import { Collection, Entity, ManyToMany, ManyToOne, PrimaryKey } from '@mikro-orm/core';
 import { Assignment } from './assignment.entity.js';
 import { Student } from '../users/student.entity.js';
 import { GroupRepository } from '../../data/assignments/group-repository.js';
@@ -20,10 +20,8 @@ export class Group {
     @PrimaryKey({ type: 'integer', autoincrement: true })
     groupNumber?: number;
 
-    @ManyToMany({
-        entity: () => {
-            return Student;
-        },
+    @ManyToMany(() => {
+        return Student;
     })
-    members!: Student[];
+    members!: Collection<Student>;
 }
diff --git a/backend/src/entities/users/student.entity.ts b/backend/src/entities/users/student.entity.ts
index 7ad8c9b3..c5632e84 100644
--- a/backend/src/entities/users/student.entity.ts
+++ b/backend/src/entities/users/student.entity.ts
@@ -19,4 +19,12 @@ export class Student extends User {
         return Group;
     })
     groups!: Collection<Group>;
+
+    constructor(
+        public username: string,
+        public firstName: string,
+        public lastName: string
+    ) {
+        super();
+    }
 }
diff --git a/backend/src/services/groups.ts b/backend/src/services/groups.ts
index 65e111fb..2f2d0a14 100644
--- a/backend/src/services/groups.ts
+++ b/backend/src/services/groups.ts
@@ -83,14 +83,11 @@ export async function createGroup(
 
     const groupRepository = getGroupRepository();
     try {
-        console.log('EEEEE');
         const newGroup = groupRepository.create({
             assignment: assignment,
             members: members,
         });
-        console.log('OOOOOO');
         await groupRepository.save(newGroup);
-        console.log('AAAAAA');
 
         return newGroup;
     } catch(e) {