Cups, toilet paper rolls, spoons, tape, paper, popsicle sticks, cans
rubberbands, and marshmallows. (or any othermaterial you think would be
interesting to add to the mix.)
For the "cannons" you can use marshmallows or small foil or tape balls. Anything soft will do.
The catapult must be able to stand by itself.
Here is a link to a video that shows students working together to create a catapult. This will give you the idea behind the project, but by all means do not make something that big. There are lots of ideas about how to build a catapult on the internet. You can google search "how to build a catapult for students."
You may also work on the project with someone else. The catapult is due Monday.