In our study of Leonardo Da Vinci as an inventor, the kids had a chance to build a catapult with materials they could find in my room. Loved their inventiveness. They had to problem solve and rebuild as they worked to make their catapult fling their fuzzy over the castle walls. 🙂 After testing their catapult, they used DoInk Green Screen and iMovie to bring their catapult to life. Enjoy.