I've posted this lesson previously HERE where you can find all the steps.
I found the lesson HERE on the School Specialty website.
This project has evolved to include not only reptiles, but any animal with patterns essentially. The goal is to somewhat camouflage it onto the background. By adding cardboard squares underneath the animal, the animals pops off the page in a low relief style.
I don't know about your students but my students have a love/hate relationship with both chalk and oil pastels! I love chalk pastels though they are messy. But I love the velvety blending capabilities it has especially on a rich black construction paper.
Some Grade 7-9 finished artworks: