Caillou's picnic is an episode in Season 1.
Leo and Caillou's family are going on picnic. They arrive at some forest area in country and find some picnic tables and have lunch after they finish eating Caillou and Leo want to go exploring Boris tells them not go to far away. Caillou and Leo stay near the picnic tables and find a field and it they find a big log by the side of the path and play with some large sticks until a rain storm starts. They find Boris, Doris and Rosie waiting for them. They look for a place to stay dry. They find a cave and stay in it until the storm ends and after that Leo and Caillou's family go for a walk.