The preschool has a visitor - Liz, a musician. She shows the kids all sorts of instruments and Caillou is excited when he's chosen to be the orchestra's 'conductor'. In fact, he's so excited, he can't stop conducting those around him - at preschool and even at home! When Caillou refuses to share his conductor's baton he soon learns how easy it is to hurt other's feelings - and how it feels better to give others a turn.
