S4·E57 Caillou's Collection

In the park Caillou starts a new hobby – collecting rocks! He finds out that Grandpa has a rock collection too, and they go to the quarry where Caillou watches a worker break up big stones into smaller ones. Caillou gets to pick out a rock for Grandpa that ends up in Grandpa’s new rock garden. Which gives Caillou an idea for the perfect spot to put his own rocks.