Ball rolling experimental design

Here are the results from yesterday’s discussion of the un-homework assignment #1: What type of ball rolls the farthest? It was a fascinating discussion!

rolling ball experimentThe first response was…”huh???? I don’t get it!” Which was pretty much what I expected. But, as you can see from the notes that I took, the children started asking questions; I simply recorded what they said. Soon, we began to explore the question with a surprisingly scientific outlook. Here’s a summary of our thinking. This thinking may help you devise an experiment to answer the question.

What to roll? Size, shape (footballs, for instance???), how many? What will matter? Will heavy ones roll farther? Light ones? Bouncy ones?

Where to roll? What kind of surface matters? Slippery? Hard? Soft? Will different balls roll farther on different surfaces? (We decided that the surface needed to be the same one for each ball, so it was fair.)

Fairness. Our rolls need to be fair. Using Annika’s wonderful word, We need to launch the balls in a fair way, so one isn’t launched with more force than another. One method Isaac brought up was they could be rolled down the same ramp. Others talked about how they could throw a ball the same; Kadin and others thought that the same person could throw the ball and try to be fair. We decided that the surface needs to be the same for each ball, though.

Measuring and recording. How will we measure the distance? How will we keep track of the distance (create a table? write down the distances?) Will we record only forward distance, or sideways distance, too?

Trials. How many times should we roll each ball? (We worried that one roll might not be accurate enough…) We thought at least 3 times each, but maybe more to make sure?

So, there’s some of our thinking. I’m impressed with the way the children were able to think through experimental design — thinking about isolating variables (though we didn’t talk that way, I’ll introduce those terms later), thinking about how to measure and record results, thinking about what makes a fair try, and thinking about doing several trials to make sure that what we find out is really true and not just a random chance event.

To get to this level of thinking is why we’re doing these projects in the first place!

Remember, if your child does decide to do this experiment, talk it through, plan it out, and try to record some of the experiment on video or photo. That will make for a nice presentation at the end.

We have about 35 days to post our results if we want to be included in Franki’s collection.