I got this idea from Let's Promote Play, where they have a much nicer apparatus than what you see here. I'd been hoping to find the time to build one of my own, but instead just re-purposed the PVC pipe from one of our painting pendulums and came up with this monstrosity. (I wound up having to add some pipe to brace the front and back to give it more stability, but you get the idea.)
I used our egg beater syle hand drill to make holes in the tennis balls and, after some effort, managed to insert links from our plastic chain-link set to serve as hooks, then hung them from various lengths of string. If we'd had small foam blocks it would have been smart to have used those, but these wooden alphabet blocks were all I had to the purpose.
The simple pendulum is a more complicated concept for preschoolers than is readily apparent to the adult mind. It took some of them several attempts to construct a building tall enough to successfully knock down. Others wanted to just throw the ball at the blocks and were either frustrated by the limitations of the string or would send blocks flying across the room, which is clearly not an activity for a full classroom. Some wanted to hold the ball by the string, in effect shortening the pendulum for their efforts. A couple just thought the idea was to knock down block towers (granted, a fun activity in its own right) and couldn't quite grasp the point of employing the intervention of a ball on a string.
But as our free play time wore on, the experimentation began to yield fruit. For instance, Isak discovered that if he swung his pendulum from one direction, he then had to pick all of his blocks up off the floor, while if he came at it from another direction most of them stayed on the table, saving him the work. He and Ariya worked together on the discovery that if you built your tower in a different place on the table, you had to build it taller in order for the ball to successfully knock it down. Thomas tried out various types of building, ultimately seeking to construct something that the balls could not knock down even when they made contact. He started with "thicker" buildings, then had the idea of building them against the "back board" you can see in the pictures.
Thomas' mom Amanda did a lot of great, patient teaching here. I don't think the kids are done playing with this.
We also got to use our full bodies to explore pendulums.
I hung this foam ball on a rope from the ceiling over our block area. The construction pylon is there to force the kids to target their block tower via a circuitous route rather than just tossing the ball directly at their target in a straight line. Again, the kids had to do a lot of experimentation to figure it out. For instance, most of them needed help to figure out the advantages of starting with a straight rope, then swinging the ball in a gentle arc around the post. There was also a lot of social learning going on as they negotiated the concept of taking turns, not blocking one another's efforts, and re-building the towers. For quite some time, Finn V. graciously took on the unofficial job of building structures for his friends, just so long as he got his own chance to swing the pendulum when his turn rolled around.
At one point we removed the blocks and a group of us formed a circle around the pylon to play catch with the ball. It wasn't always easy to get the ball to go to the friend to whom you were trying to send it. Most challenging of all was trying to get the ball to go to the person right next to you because gravity really wants to take it to the person across from you!
Isak's mom Leslie made what could have been a chaotic activity into a very successful learning experience.
When we went outside, I hung this long pendulum from a tree branch, but mainly all they sought to do was throw the ball over the fence, then fish it back using long sticks. We had to put an end to this game after kids started accidentally whacking each other in the head.
Again, I don't think the children are anywhere near being done with this. It will have to revisit the classroom (although perhaps not the playground) soon.
(Note: These two activities were going on simultaneously, along with a sensory table full of drinking straws and scissors, a fairly complicated art project, a game of Hi Ho Cheerio, play dough, "discovery bottles," a full-on home center, and snack. Each activity in its own right one that requires some level of adult involvement. This was a day that could only happen in a cooperative preschool, with a roomful of engaged "assistant teachers." Not only that, but I was free to roam from station to station to observe and assist in the great learning that was taking place in every corner of the room.)