public ActionResult UpdateTeachersInClass(string classId, List<string> teacherId)
 {
     try
     {
         ClassService classService = new ClassService((SiteUser)Session["SiteUser"], new dbTIREntities());
         return Json(classService.UpdateTeachers(Convert.ToInt32(classId), teacherId));
     }
     catch (Exception ex)
     {
         Logging log = new Logging();
         log.LogException(ex);
         return View("GeneralError");
     }
 }