Not The End Of The Story

A couple weeks back, I wrote about a giant catapult our 5's class built, inspired by Henry who had arrived with a length of bicycle inner tube that he was hoping we could use to build such an apparatus, or, alternatively, a "giant slingshot."

That was not the end of the story: it's ongoing as most of them ought to be in a play-based curriculum.

When last we left our efforts, we'd indeed managed to create a giant catapult, albeit one with very little actual power, which is not such a bad thing considering we've been launching various objects into the midst of a crowded playground. It's other flaw, a fatal one, was that we had never quite figured out how to securely anchor the pivot end of our catapult's arm, which meant that it would, as it launched our projectile, simultaneously kick out at the bottom, tossing the tangle of wood, rocks, logs and whatnot that we were using to hold it in place a few feet forward as well. Gus considered this a feature of our invention, saying that we had a catapult up top and a "cannon" on the bottom. This optimism faded fairly quickly, however, as we came to understand that this meant reassembling the entire machine after each launch.

We left the catapult in place until the following day, when I asked Audrey's dad Caleb to support the kids with their tinkering. After about a half hour, a couple of chunks of 2X4, and some nails later, they had fashioned a solution to the problem.

Depending on the projectile, we were achieving a good 10-15 feet with our launches, not the "all the way over the fence" of our original aspirations, but far enough to let it ride for several days as various group of kids experimented with it.

As interest waned, I suggested we take up the second of Henry's ideas: a giant slingshot. We tied several shorter pieces of inner tube together to make long one (a feature of using inner tubes for these purposes is that knots are both tight and flexible), then tied it between a couple trees. Our results were fine, but honestly, I'd done much of the work and the kids were only mildly interested after the first flurry of turn taking.

That's when Tristan began to agitate to go back to the catapult, other kids joining him in his assertion that catapults are better than slingshots. Now, I had other plans for our workbench area and told them so, wondering where else we could build a catapult, to which William replied, "We could just make it out of the sling shot." This was met with general enthusiasm. I pointed out that the arm we had previously built was resting up against the fence behind the workbench. Our first effort was to lean it against the slingshot, pull it back, and let go, which resulted in launching the entire arm several feet into the sand pit, while dropping the intended projectile directly to the ground.

Tristan said, "We need something to make it stop." We all, I think knew what that meant. After trying some large rocks, piles of logs and various other objects from around the place, someone suggested we use the "big wood box," referring to our large art crate which we've been living with for the past couple years. "We could put the catapult inside the box." The crate is a heavy object and took several of us, with adult assistance, to wrestle it up the hill and into place. By placing the pivot end of the arm into the box, we did manage to get our projectiles to fly when the arm hit the side of the crate, although in the aftermath the entire arm came flying out as well. 

Xander suggested, "We could put rocks or logs or something like that in the box to hold it in there."

Within minutes we'd pretty much filled the box with rocks, logs, and other portable items. This did hold the arm in place, although it also meant that we couldn't pull it back at all. It was at this point that we lost many of our builders to other games, leaving the rest of us to ponder the dilemma. Finally, Xander said, "We need something squishy in there so it can go back, but not too far back." I understood what he meant and it fed right into a solution I'd been thinking about. I asked, "Do you mean something like a tire?"

"That might be good."

There were a lot of rocks and logs to remove from the crate, a project that I knew would take the kids a long time, so I pitched in, helping to make short work of it, and into the vacuity we tossed the tire, which fit snugly into the crate, pinning the end of the arm against the side of the crate. After a couple tests to confirm that we could now pull the arm back, we were feeling confident about our catapult so made a big deal about our first launch, calling our friends over to witness it. And it worked, launching a small rubber ball a good 25 feet. Subsequent launches, however, revealed another flaw in our design. With each launch, we discovered, the tension caused the tire to slide a few inches back in the box, ultimately loosening things up enough that the entire launch arm, as it had before, ejected from its seat.

Leon thought we ought to go back to the logs and rocks idea, but only putting them "behind the tire" so it wouldn't slide. That worked to hold the tire in place, we discovered, although there was still a problem with "creep" as the end of the arm continued to eventually work its way out of the box. This is when Tristan dropped a log in front of the arm, while I used my superior physical strength to wedge it in tightly.

It's still an imperfect thing from an engineering perspective, but as something with which to tinker, it could not be better, being the center of a couple weeks of nearly constant play, at least for a certain group of boys. After several days of testing various projectiles, we've most recently settled on using it to scatter wood chips. We've experimented with tying ropes to the arm and not. We've made enough of a study of it's aim and distance to stand just out of range and challenge one another to hit us, or even better, to use some sort of shield to protect ourselves. Yesterday, we even built a shelter just beneath the catapult protecting ourselves from both the projectiles as well as the arm of the catapult which still occasionally jumps from it's nest of tire, rocks and logs. We've also learned how to repair it ourselves.

It's a story we're still telling. I'll keep you updated.

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