protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            //驗證身份
            Person myPerson = new Person();
            if (myPerson.Role == Person.LoginRole.Administrator || myPerson.Role == Person.LoginRole.SchoolAdmin || myPerson.Role == Person.LoginRole.Student || myPerson.Role == Person.LoginRole.Parent)
            {
                Response.Redirect("~/Default.aspx");
            }
            DataLayer dl = new DataLayer();
            DataTable dtCourseByGrade = dl.GetTeacherCourseByGradeID(Request["grade_id"]);
            ViewState["CourseByGrade"] = dtCourseByGrade;

            Show();
        }
    }