Recently our class began studying variables. We defined it as the following:

Variable-Anything you can change in an experiment that might affect the outcome.

This lead us to run some controlled experiments. First, we looked at a particular pendulum system. Students built them with a 38 cm string, a paper clip and a penny. Next, I asked kids… “How many swings will are pendulums complete in 15 seconds?” Kids made several predictions. The teams came up with mixed results that didn’t quite make sense. When I probed a bit further we found we needed to standardize our process for the investigation. Everybody has to follow the same steps.

Later, the class broke down the variables for the pendulums.

length of string
release height
mass (pennies)
pushing/pulling vs. dropping
type of string

This lead to more tests. We wondered…

How does release height affect the number of swings in 15 seconds?

How does mass affect the number of swings in 15 seconds?

We concluded that when we ran controlled experiments with the variables above, there was no significant change in the number of swings our pendulums completed. As a result, we looked back at the variable list and we made the decision to test swinger length. The videos below show the class experimenting. Some of the pendulums were so large we had to start them from a position near or on the ceiling!

Do you remember what we discovered? What was the trend we observed?