What doesn't this pen do? It functions as a pencil, pen, highlighter, and PDA stylus. As you can see, it also operates as a ruler.
If you find that you are always misplacing your school tools, you may find it helpful to invest in one of these . . . along with a pencil pouch to keep it in. In a pinch, you'll have almost everything you need to write, draw, measure and surf.