This includes lab directions, photos of set up and a student lab sheet. This lab uses crayons to model how rocks change. It starts with sediment, becomes sedimentary, partially melts to become metamorphic and the completely melts to become igneous. I used this lab with 7th graders as an introduction to the rock cycle and followed it up with more in-depth activities.
This is a link to the crayons I used (270 for $23): https://www.amazon.com/gp/product/B0186H7KFG/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1