diff --git a/episodes/Enhancing-coding-efficiency.md b/episodes/Enhancing-coding-efficiency.md
index a0be109..f2dbe45 100644
--- a/episodes/Enhancing-coding-efficiency.md
+++ b/episodes/Enhancing-coding-efficiency.md
@@ -19,6 +19,12 @@ TODO
 
 TODO
 
+::::::::::::::::::::::::::::::::::::: challenge 
+
+Challenge example
+
+::::::::::::::::::::::::::::::::::::::::::::::::
+
 ::::::::::::::::::::::::::::::::::::: keypoints 
 
 TODO