thinair Boulder, Colorado. elevation 5400 feet.

Reenacting Galileo's experiments with Gravity

Alan Kay and computational thinking part 4.

Alan Kay suggests we have kids reenact Galileo's experiments with Gravity. [The Real Computer Revolution Hasn't Happened Yet p.15]

A nice "real science" example for 11 year olds is to investigate what happens when we drop objects of different weights.

The children think that the heavier weight will fall faster. And they think that a stopwatch will tell them what is going on. But it is hard to tell when the weight is released, and just when it hits.

In every class, you'll usually find one "Galileo child". In this class it was a little girl who realized: well, you don't really need the stop watches, just drop the heavy one and the light one and listen to see if they hit at the same time.

These are powerful experiences: the frustration of measuring with a stopwatch, the excitement of solving that problem with essentially a race to the ground, and the unexpected result that the heavy and light balls always tie. But the real excitement for me is in his examples of how to use computers to enhance the experiment.

It starts with the use of a digital video camera to record the fall of a ball. In the software we pull out several frames from the video and have the students use computer graphics to measure the difference in position from one frame to the next. We can remind the students of their experience in measuring the tire -- this technique gives us a measurement tolerance of one pixel, so we won't get exact results.

Through these measurements the students discover constant acceleration. Remember, they have seen velocity and acceleration when they programmed their digital car earlier. Now they can connect those lessons to their own direct measurements of gravity. In other words, we've begun teaching elementary aged children physics and Newtonian mechanics.

Even better, they can repurpose the earlier exercises with car to create a model of gravity that matches their experimental data. This is an example of the kind of work real scientists are doing all over Boulder -- creating elaborate software models and verifying and adjusting the models against experimental data.

Kay goes on to suggest the kids use their new knowledge about modeling gravity to create a Lunar Lander video game.