private void checkAttendanceToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Teacher       teacher = new Teacher(string.Empty, string.Empty, DateTime.Now);
            Classes       group   = EduManagement.Instance.Classes.ElementAt(0);
            Student       student = new Student(string.Empty, string.Empty, DateTime.Now, group);
            NewAttendance form    = new NewAttendance(teacher, student, true);

            form.Show();
        }
        private void btnAdd_Click(object sender, EventArgs e)
        {
            Teacher       teacher           = new Teacher(string.Empty, string.Empty, DateTime.Now);
            Classes       group             = EduManagement.Instance.Classes.ElementAt(0);
            Student       student           = new Student(string.Empty, string.Empty, DateTime.Now, group);
            NewAttendance NewAttendanceForm = new NewAttendance(teacher, student, true);

            NewAttendanceForm.Show();
            NewAttendanceForm.FormClosed += NewAttendanceForm_FormClosed;
        }