diff --git a/PacticeSolution/ListSample/Converter/AgeToRangeConverter.cs b/PacticeSolution/ListSample/Converter/AgeToRangeConverter.cs
new file mode 100644
index 0000000..afb24a9
--- /dev/null
+++ b/PacticeSolution/ListSample/Converter/AgeToRangeConverter.cs
@@ -0,0 +1,27 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Data;
+
+namespace ListSample.Converter
+{
+    [ValueConversion(typeof(int), typeof(string))]
+    internal class AgeToRangeConverter : IValueConverter
+    {
+        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (value == null) 
+                return null;
+
+            return (int)value >= 40 ? "OB Group" : "YB Group";
+        }
+
+        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            return null;
+        }
+    }
+}
diff --git a/PacticeSolution/ListSample/ListSample.csproj b/PacticeSolution/ListSample/ListSample.csproj
index 2c18da2..9530d10 100644
--- a/PacticeSolution/ListSample/ListSample.csproj
+++ b/PacticeSolution/ListSample/ListSample.csproj
@@ -55,6 +55,7 @@
       <Generator>MSBuild:Compile</Generator>
       <SubType>Designer</SubType>
     </ApplicationDefinition>
+    <Compile Include="Converter\AgeToRangeConverter.cs" />
     <Compile Include="Resources.Designer.cs">
       <AutoGen>True</AutoGen>
       <DesignTime>True</DesignTime>
diff --git a/PacticeSolution/ListSample/MainWindow.xaml b/PacticeSolution/ListSample/MainWindow.xaml
index f55b15a..938b650 100644
--- a/PacticeSolution/ListSample/MainWindow.xaml
+++ b/PacticeSolution/ListSample/MainWindow.xaml
@@ -33,7 +33,7 @@
                 <TextBlock Grid.Column="1" Grid.Row="0" HorizontalAlignment="Center" VerticalAlignment="Center"
                            Text="Name: "/>
                 <TextBlock Grid.Column="2" Grid.Row="0" HorizontalAlignment="Center" VerticalAlignment="Center"
-                           FontSize="18" FontWeight="Bold"
+                           FontWeight="Bold"
                            Text="{Binding Name}"/>
                 <Button x:Name="btnDelete" Grid.Column="3" Grid.Row="1" Margin="3"
                         Content="Delete"
@@ -54,8 +54,31 @@
     </Window.Resources>
     
     <Grid>
-        <ListBox x:Name="lbStudentList" IsSynchronizedWithCurrentItem="True" HorizontalContentAlignment="Stretch"
+        <Grid.RowDefinitions>
+            <RowDefinition Height="*"/>
+            <RowDefinition Height="Auto"/>
+        </Grid.RowDefinitions>
+        
+        <ListBox x:Name="lbStudentList" Grid.Row="0" IsSynchronizedWithCurrentItem="True" HorizontalContentAlignment="Stretch"
                  ItemTemplate="{StaticResource studentTemplate}"
-                 ItemsSource="{Binding}"/>
+                 ItemsSource="{Binding}">
+            <ListBox.GroupStyle>
+                <GroupStyle>
+                    <GroupStyle.HeaderTemplate>
+                        <DataTemplate>
+                            <TextBlock Background="Black" Foreground="White" FontSize="18" FontWeight="Bold" HorizontalAlignment="Center">
+                                <TextBlock Text="{Binding Name}"/> (<TextBlock Text="{Binding ItemCount}"/>Person)
+                            </TextBlock>
+                        </DataTemplate>
+                    </GroupStyle.HeaderTemplate>
+                </GroupStyle>
+            </ListBox.GroupStyle>
+        </ListBox>
+
+        <StackPanel Grid.Row="1">
+            <Button x:Name="btnGroup"
+                    Content="Gourpage"
+                    Click="btnGroup_Click"/>
+        </StackPanel>
     </Grid>
 </Window>
diff --git a/PacticeSolution/ListSample/MainWindow.xaml.cs b/PacticeSolution/ListSample/MainWindow.xaml.cs
index 2d61975..82132e3 100644
--- a/PacticeSolution/ListSample/MainWindow.xaml.cs
+++ b/PacticeSolution/ListSample/MainWindow.xaml.cs
@@ -1,6 +1,8 @@
-using ListSample.Model;
+using ListSample.Converter;
+using ListSample.Model;
 using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
@@ -38,5 +40,14 @@ namespace ListSample
             Student student = (Student)button.DataContext;
             _studentList.Remove(student);
         }
+
+        private void btnGroup_Click(object sender, RoutedEventArgs e)
+        {
+            ICollectionView list = CollectionViewSource.GetDefaultView(_studentList);
+            if (list.GroupDescriptions.Count == 0)
+                list.GroupDescriptions.Add(new PropertyGroupDescription("Age", new AgeToRangeConverter()));
+            else
+                list.GroupDescriptions.Clear();
+        }
     }
 }