public function index()
 {
     if (Auth::user()->role == 'student') {
         $quizzes = Quiz::all();
         foreach ($quizzes as $quiz) {
             $quiz['participated'] = Auth::user()->student()->first()->quizzes()->get()->find($quiz->id) ? true : false;
         }
         return $quizzes->toJson();
     }
     return Quiz::all()->toJson();
 }
 /**
  * Display a listing of the resource.
  *
  * @return Response
  */
 public function index()
 {
     $quizzes = Quiz::all();
     return view('site.quizzes.index')->with('quizzes', $quizzes);
 }