Paint Stirrer Crossbows and Popsicle Stick Catapults: Homeschool STEM with Rubber Band Engineer

We're not exactly lacking STEM studies here in our homeschool, but I thought that the kids might like a change from robotics, so I offered them the opportunity to create something from this fun little book:

Because what could possibly be more charming than a book with a real, actual rubber band on it?!? Or more tempting than a cover that boasts the instructions for a "slingshot rifle" inside?!?

Here is Will's ballpoint pen crossbow, made from paint stirrers, bamboo skewers, a lot of hot glue, and some twine:

I don't have any photos of it in action because I didn't realize that its first shot would be its last! Will suspects that the twine she used was too stiff; she thinks she needs something with the slightest bit of stretch so it can hold a little more potential energy without putting so much pressure on the paint stirrer. 

Stay tuned for Version 2!

Syd's wooden pencil catapult was more successful overall--

--but then, she did have an assistant for its construction:

It turns out that a catapult made from duct tape, wooden pencils, and a plastic lid, shooting a cork tied to yarn, is quite the thing to keep a young cat entertained:

An automatic winder would improve the catapult's playability here, I'm told, as much of the fun for the cat involves chasing the yarn as it's being wound up again for another go:

This was definitely a good book for encouraging the tinkering aspect of STEM: the contraptions all worked fairly well, with build instructions clear enough that a kid could follow them independently, and yet they always had the potential to work better, or in a different way, with some overall easy-to-implement ideas that kids can dream up. 

In this way, rather than each contraption being the end goal, it's more the starting point (it reminded me quite a lot of the time the kids made paper roller coasters, actually!). A kid uses her fine-motor skills and ability to follow directions to create an instrument upon which her own research, ideas, refinements, and tinkering do the work to teach her the physics, math, and engineering concepts hidden within each contraption.

And if you end up with a ballpoint pen that's turned into a projectile, all the better!

P.S. Want to hear more about paper roller coasters and paint stirrer crossbows? Follow my Craft Knife Facebook page for more projectile adventures as they happen!