Colorful sketches

What we used:

paper
crayons-black and other random colors
or markers for the colors
paper clip

What we did:
First make a rainbow type design with different color crayons (but we discovered that markers actually work better)

Then cover the colors with black crayon. Press hard and cover up the colors as much as possible. Unfold a paper clip and use it to draw a design. The paper clip will scrape away the black to reveal the colors underneath.
I used to do this as a kid and thought it was great. The boys thought so too!