public ActionResult Mark(string username, string classId, int classNumber)
        {
            HomeworkModel homeworkModel = new HomeworkModel();

            ViewBag.homework = homeworkModel.GetHomework(username, classId, classNumber);
            return(View());
        }
        public ActionResult SubmitHomework(string classId, int classNumber)
        {
            string        username      = HttpContext.Request.Cookies["login"]["name"];
            HomeworkModel homeworkModel = new HomeworkModel();

            ViewBag.homework = homeworkModel.GetHomework(username, classId, classNumber);
            return(View());
        }