diff --git a/_toc.yml b/_toc.yml
index 6c13e5e..3cbfd9f 100644
--- a/_toc.yml
+++ b/_toc.yml
@@ -6,7 +6,7 @@ root: intro
 chapters:
 - file: material/cards-1
 - file: material/cards-2
-#- file: material/cards-3
+- file: material/cards-3
 #- file: material/cards-4
 #- file: material/cards-5
 #- file: material/cards-6