I did this project while student teaching and loved doing it just as much, if not more, than the kids did. I recently taught this to my middle school class along with a lesson in Pop Art.
It's a great way to practice observational drawing in a safe setting. If you don't get it just right, it doesn't look too bad, since it's a drawing of something that is crushed already! It is also a good observational drawing exercise, since in order to draw the can, you can't easily draw a pre-concieved idea of what a can looks like; you are forced to look carefully at each line, shape and plane in order for it to work together as a whole. Even though we were essentially drawing a piece of "trash", they ended up being such beautiful works of art!
Materials: pencil, ink and watercolors