diff --git a/notes.md b/notes.md
index 049b055..e5ac000 100644
--- a/notes.md
+++ b/notes.md
@@ -14,7 +14,7 @@ The board is shown using TTTView with the methods for print_board() and get_acti
 ### Choosing which action to play on a turn
 A player can choose which action to play on a turn from within the TTTHumanPlayer with the method for choose_action().
 
-## Checkpoint 2 Notes
+## Checkpoint 3 Notes
 
 ### TTT Strategy
 
diff --git a/ttt/game.py b/ttt/game.py
index 2f0e302..9678d14 100644
--- a/ttt/game.py
+++ b/ttt/game.py
@@ -58,4 +58,15 @@ class TTTGame:
 
     def check_winner(self, state, symbol):
         "Checks whether the player with `symbol` has won the game."
+        currentState = state["board"]
+        for i in range (0,7,3):
+            if currentState[i] == symbol and currentState [i+1] == symbol and currentState [i+2] == symbol:
+                return True
+        for i in range (3):
+            if currentState[i] == symbol and currentState [i+3] == symbol and currentState [i+6] == symbol:
+                return True
+        if currentState[0] == symbol and currentState [4] == symbol and currentState [8] == symbol:
+            return True
+        if currentState[2] == symbol and currentState [4] == symbol and currentState [6] == symbol:
+            return True
         return False