private void InitializeStudents()
        {
            NamesTable.Clear();
            Backup.Clear();

            if (InGrade.Count == 0 && TeachersInGrade.Count == 0)
            {
                NotFoundStack.IsVisible = true;
            }
            else
            {
                NotFoundStack.IsVisible = false;
            }

            int    count  = 0;
            string filter = StudentSearch.Text == null ? "" : StudentSearch.Text.Trim().ToLower();

            foreach (var s in InGrade)
            {
                ViewCell cell = new ViewCell()
                {
                    Height = 70
                };

                StackLayout sl = new StackLayout()
                {
                    Orientation = StackOrientation.Horizontal, BackgroundColor = Color.FromHex("#FFFFFF")
                };
                sl.Padding = new Thickness(10, 0, 10, 0);
                sl.Children.Add(new Label()
                {
                    Text = s.Key, IsVisible = false
                });

                CircleImage ci = GetPhoto(s, true);

                sl.Children.Add(ci);

                CheckBox cb = new CheckBox()
                {
                    HorizontalOptions = LayoutOptions.EndAndExpand
                };

                Label l = new Label()
                {
                    Text                  = s.Value,
                    VerticalOptions       = LayoutOptions.Center,
                    VerticalTextAlignment = TextAlignment.Center,
                    TextColor             = Color.Black,
                    FontSize              = 16,
                    Padding               = new Thickness(30, 0, 0, 0)
                };
                cell.Tapped += TableCell_Tapped;

                sl.Children.Add(l);
                sl.Children.Add(cb);

                cell.View = sl;

                Backup.Add(cell);

                if (Attendance.AttendedToday(s.Key, DatePicker.Date))
                {
                    cb.IsChecked = true;
                }
                else
                {
                    cb.IsChecked = false;
                }

                if (s.Value.ToLower().Contains(filter))
                {
                    // make visible
                    NamesTable.Add(cell);
                    count++;
                }
            }
            //NamesTableRoot.Clear();
            NamesTableRoot.Add(NamesTable);
        }