This is a classic in the art room: scratch art. Students colored a sheet of paper with very thick crayon using bright colors. The next week, students painted over the crayon with black tempera paint that has a bit of dishsoap added to it (it helps with adhesion.) They will then make a sketch of their idea for their scratch art on copy paper. The following week students will scratch their design with a wooden stylus. The key to a successful project is to remind kids that less is more. They should stick to their plan, and not go overboard on adding designs when scratching.
Color...
Paint...
Scratch!