private void Teacher_Homepage_Load(object sender, EventArgs e)
 {
     TeacherAddExam.Hide();
     TeacherCorrectExam.Hide();
     TeacherStatistics.Hide();
     TeacherClassManagement.Hide();
     TeacherCalendar.Hide();
     TeacherProfile.Hide();
 }
 private void btnProfile_Click(object sender, EventArgs e)
 {
     TeacherAddExam.Hide();
     TeacherCorrectExam.Hide();
     TeacherStatistics.Hide();
     TeacherClassManagement.Hide();
     TeacherCalendar.Hide();
     TeacherProfile.Show();
     TeacherProfile.BringToFront();
 }