My child attends an Atrium religious ed class at St. Charles. It is based on the Montessori method. We love it. I know a parish (St. Louis) closer to our home offers a Sat AM class. Worth checking out. They learn about the liturgical seasons, parts of the mass and it's all hands on. It's not exclusive to the CAtholic church. I think some other churches offer it too. Here is the link to learn more about the Atrium program and find one near you.
http://www.cgsusa.org/atrium.aspx