diff --git a/Toolkit.Foundation/ICollectionSynchronization.cs b/Toolkit.Foundation/ICollectionSynchronization.cs
new file mode 100644
index 0000000..10d67c9
--- /dev/null
+++ b/Toolkit.Foundation/ICollectionSynchronization.cs
@@ -0,0 +1,3 @@
+namespace Toolkit.Foundation;
+
+public interface ICollectionSynchronization<TItem>;
\ No newline at end of file
diff --git a/Toolkit.Foundation/ICollectionSynchronizationExtensions.cs b/Toolkit.Foundation/ICollectionSynchronizationExtensions.cs
new file mode 100644
index 0000000..c368e40
--- /dev/null
+++ b/Toolkit.Foundation/ICollectionSynchronizationExtensions.cs
@@ -0,0 +1,7 @@
+namespace Toolkit.Foundation;
+
+public static class ICollectionSynchronizationExtensions
+{
+    public static int IndexOf<TItem>(this ICollectionSynchronization<TItem> synchronization,
+        TItem item) => synchronization is IList<TItem> collection ? collection.IndexOf(item) : -1;
+}
diff --git a/Toolkit.Foundation/IIndexable.cs b/Toolkit.Foundation/IIndexed.cs
similarity index 69%
rename from Toolkit.Foundation/IIndexable.cs
rename to Toolkit.Foundation/IIndexed.cs
index dcf42af..43f70d3 100644
--- a/Toolkit.Foundation/IIndexable.cs
+++ b/Toolkit.Foundation/IIndexed.cs
@@ -1,6 +1,6 @@
 namespace Toolkit.Foundation;
 
-public interface IIndexable
+public interface IIndexed
 {
     public int Index { get; }
-}
\ No newline at end of file
+}
diff --git a/Toolkit.Foundation/IKeyed.cs b/Toolkit.Foundation/IKeyed.cs
new file mode 100644
index 0000000..dfaae3b
--- /dev/null
+++ b/Toolkit.Foundation/IKeyed.cs
@@ -0,0 +1,6 @@
+namespace Toolkit.Foundation;
+
+public interface IKeyed<T>
+{
+    public T Id { get; }
+}
\ No newline at end of file
diff --git a/Toolkit.Foundation/ISynchronizationCollection.cs b/Toolkit.Foundation/ISynchronizationCollection.cs
deleted file mode 100644
index 34ddd27..0000000
--- a/Toolkit.Foundation/ISynchronizationCollection.cs
+++ /dev/null
@@ -1,6 +0,0 @@
-namespace Toolkit.Foundation;
-
-public interface ISynchronizationCollection<TItem>
-{
-    int IndexOf(TItem item);
-}
diff --git a/Toolkit.Foundation/Observable.cs b/Toolkit.Foundation/Observable.cs
index eb0055a..f3a7583 100644
--- a/Toolkit.Foundation/Observable.cs
+++ b/Toolkit.Foundation/Observable.cs
@@ -1,4 +1,5 @@
 using CommunityToolkit.Mvvm.ComponentModel;
+using System.ComponentModel;
 
 namespace Toolkit.Foundation;
 
@@ -140,4 +141,11 @@ public partial class Observable<TKey, TValue> : Observable
         Key = key;
         Value = value;
     }
+
+    partial void OnValueChanged(TValue? value) => OnValueChanged();
+
+    protected virtual void OnValueChanged()
+    {
+
+    }
 }
\ No newline at end of file
diff --git a/Toolkit.Foundation/ObservableCollection.cs b/Toolkit.Foundation/ObservableCollection.cs
index 57b1f85..7c8d99a 100644
--- a/Toolkit.Foundation/ObservableCollection.cs
+++ b/Toolkit.Foundation/ObservableCollection.cs
@@ -18,7 +18,7 @@ public partial class ObservableCollection<TItem> :
     IList,
     IReadOnlyList<TItem>,
     INotifyCollectionChanged,
-    ISynchronizationCollection<TItem>,
+    ICollectionSynchronization<TItem>,
     IServiceProviderRequired,
     IServiceFactoryRequired,
     IMediatorRequired,