protected void Page_Load(object sender, EventArgs e) { //Tafe_DataTier dt = new Tafe_DataTier(); //List<Student> students = dt.viewStudents(); // for some reason, these contents are repeatedly added to drop down list! Why? foreach (Student s in students) { StudentDropDownList.Items.Add(s.StudentID); } courses = new List <Course>(); bill = 0; }