diff --git a/chap4_the_mvc_pattern/TheMVCPattern/Program.cs b/chap4_the_mvc_pattern/TheMVCPattern/Program.cs
index b3adcbf..030567a 100644
--- a/chap4_the_mvc_pattern/TheMVCPattern/Program.cs
+++ b/chap4_the_mvc_pattern/TheMVCPattern/Program.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 
 namespace TheMVCPattern
 {
@@ -9,4 +10,26 @@ namespace TheMVCPattern
             Console.WriteLine("Hello World!");
         }
     }
+
+    public class Member
+    {
+        public string LoginName { get; set; } // The unique key
+        public int ReputationPoints { get; set; }
+    }
+
+    public class Item
+    {
+        public int ItemID { get; private set; } // The unique key
+        public string Title { get; set; }
+        public string Description { get; set; }
+        public DateTime AuctionEndDate { get; set; }
+        public IList<Bid> Bids { get; set; }
+    }
+
+    public class Bid
+    {
+        public Member Member { get; set; }
+        public DateTime DatePlaced { get; set; }
+        public decimal BidAmount { get; set; }
+    }
 }
\ No newline at end of file