message: Added only the src file
diff: <p>
  <mat-slide-toggle (change)="onChangeActive($event)"
  [checked]="active">
  - <span *ngIf="active">Course can be seen by students</span>
  - <span *ngIf="!active">Course cannot be seen by students</span>
  + <span>Course can be seen by students</span>
  </mat-slide-toggle>
  </p>
  