Does anyone use anything fun and well, "cute", for demonstrating the earth's core? Playdoh or M&M's inside marshmallows...?? I would like some good, easy, and cheap ideas. Also, what types of activities/projects do you do for rocks and minerals? We are going on a field trip and that will take care of fossil-making and plaster of paris so I don't have to worry about that! :woot: Thanks for any ideas.