So, we did the woodblock slingshot as a way to fit a parabola to a set of student collected data. The setup is easier to show than explain.
Here’s the handout I used:
What went well:
-The discussion about the shape of the data was great. As long as multiple groups got a smooth curve, the class tended to agree that a quadratic model would work best.
-The data was pretty easy to collect. It’s just linear distance measurements, so…
What didn’t work:
-The data collection was pretty messy, it was hard to get a consistent measurement across multiple trials. And as always, some groups just decided that multiple trials weren’t necessary, so their data was all over the place.
-My handout wasn’t crystal clear about fitting the curve. I think maybe I should include hints (does your data look like a linear or quadratic model might fit?)
-The payoff wasn’t flashy. I’m thinking next time, we’ll have a contest to see whose equation can make the most accurate prediction (like closest to the edge of the table or something). They’ll have to explain their prediction, including the graph and the equation, then we’ll test it out.
Ideas for next time:
-Leave the data table blank. Let the students decide how far to pull back in order to get a good range of measurements.
-Many groups were recording the position of the block (because that’s what my instructions said, whoops), not the distance it traveled. They are different because you pull back on it, so it doesn’t start at zero. I think the better method might be to have one measuring tape, and columns in the data table for “starting position”, “final position”, and “distance traveled”.
-Use a roll of tape as the object. the woodblock would rotate as it traveled, making it hard to get accurate distance measurements. One group used a roll of tape instead and worked nicely because the spin didn’t matter.