During your Earth systems unit, you could have junior geologists cut out and create a small globe depicting the tectonic plates. You may want to do this all together, step by step as a class because it would be easy to cut all of the pieces apart when they should only be separated into four groups. Another thing to consider is how to adhere the paper to a tennis ball; regular classroom glue won't hold. Rather than a tennis ball, you could use a styrofoam ball, and rather than classroom glue, you could use rubber cement.