Persona dolls are a great way to introduce young children to ideas like other religions.
Downloadable here is a series of sessions designed for use with a persona doll to exploreIslam through special times (prayer, birth, Eid and Ramadan) special places (the mosque), special books (the Koran) and special people (Mohammad). Also available here is a series of photos of Hassan's mosque. (N.B. Out of respect for the Muslim prohibition on reproducing the human likeness Hassan doesn't appear in the mosque).