Tin foil, yarn, cardboard, and sharpies. This makes a cool low relief sculpture. Start by teaching about line variations, and color schemes (monochromatic, analogous, etc.). Cool project for 6-7th grade.
7th Grade. Topography. Cut an organic shape of construction paper. Re-trace it on another piece and copy the line only a little smaller. Continue until the pieces become small. Once all the pieces are cut out, glue together, add a small piece of styrofoam in between to get the height to really show. Try to place the styrofoam above one another to make it easier to press down once it has been built up.