diff --git a/src/break_out/model/IBall.java b/src/break_out/model/IBall.java
index b2078ce..8f6c8d5 100644
--- a/src/break_out/model/IBall.java
+++ b/src/break_out/model/IBall.java
@@ -17,4 +17,7 @@ public interface IBall {
 	// Exercise 4
 	public boolean hitsStone(ArrayList<Stone> stones);
 	public Stone getHitStone();
+
+	// Exercise 5
+	public boolean isLost();
 }
\ No newline at end of file