public Exam AddExam(int RID, int TID)
 {
     Exam newExam = new Exam { RosterID = RID, TestID = TID, score = 0};
     context.Exams.Add(newExam);
     context.SaveChanges();
     return newExam;
 }
 public void SubmitExam(Exam exam)
 {
     context.Entry(exam).State = System.Data.EntityState.Modified;
          context.SaveChanges();
 }