This is an activity that models the rock cycle starting from two or more extrusive igneous rocks that are different colored crayons, shaving them (which takes quite a while - the kids loved this part of it as they found it relaxing and "satisfying") to form a sedimentary rock by pressing the layers together into a fragile crayon rock, then putting this into a foil baking tin cup or student made tin foil cup or boat and melting it slowly on a hotplate, letting it cool to see their finally formed metamorphic rock. This can be used as an activity, exploration, or lab. It's quite simple and was one of the student's favorite days. This activity is colorful, relaxing, and informative. It should take an entire period or a little longer however you plan it. There is a one page worksheet with it to keep them on track as well along with a KEY for the teacher.