Say "hello" to the little boy named Caillou. He lives with his mommy and daddy, sister Rosie and cat Gilbert and he is getting bigger every day. His imagination is also expanding with help from his stuffed friends Matthew Theodore Bear and Rexie the dinosaur. This episode is all about growing up. What will Caillou be when he grows up? WIll he be a pack-rat like his daddy? What's it like to ride the schoolbus? Does he have to grow up if that means that someday he will be TOO old?