diff --git a/_episodes/22-scaling-up-unit-testing.md b/_episodes/22-scaling-up-unit-testing.md
index 09f3446d4..8fcdd8722 100644
--- a/_episodes/22-scaling-up-unit-testing.md
+++ b/_episodes/22-scaling-up-unit-testing.md
@@ -350,4 +350,8 @@ Using automated testing where appropriate can save us considerable time,
 especially in the long term,
 and allows others to verify against correct behaviour.
 
+## Optional exercises
+Checkout [these optional exercises]({{ site.baseurl }}{% link _episodes/25-section2-optional-exercises.md %}#exercise-customize-pylint)
+to learn more about code coverage.
+
 {% include links.md %}