Did you know that straws can make music… or rather, that if you cut drinking straws into different lengths, they will make different sounds when you blow into them? Just try it! And when you put them together, there might even be music :)
Helped my student make this catapult for a high school physics project. Used 2" scrap lumber, screws, 2 cup hooks, and a short bungee cord. Made a projectile seat out of card stock and hot glued it on. Also copied a protractor and taped it to the side for calibration. Throws a small bean bag about 10 meters (32.8 ft) at full force.
Marshmallow Catapult...you can't tell me that any boy wouldn't love this to aim at a target or someone's mouth. Watch video @ http://familyfun.go.com/crafts/crafts-by-type/educational-craft-activities/science-projects/marshmallow-catapult-874571/