The effects of gravity

At school I have been teaching about gravity and its effect on falling objects. My students conducted an experiment where they dropped various objects (paper, feather, tennis ball, golf ball) and recorded which object fell the fastest. The results were as expected...the paper took teh longest every time.

After that experiment, I challenged my students to find a way to make the tennis ball and the paper fall to the ground at the same rate. It was interesting to see what they tried...dropping it sideways, dropping it with the ball on top, dropping it from a different height....

When they had been given a few minutes to complete the task, I showed them another option. I took a piece of paper and crunched in into a ball. When I dropped the crumpled paper and the tennis ball this time, they hit the ground at the same time. This got the kids' attention.

I next asked them to try to explain why the crumpled paper fell faster than the flat paper. I assumed they would talk about the shape and air resistance. What surprised me was that many of the students actually suggested that the crumpled paper weighed more than the flat one! It was at this point that I knew I had to address this misconception.

I tried relating it to something more familiar. I asked the students if I would weigh more on a bathroom scale if I crouched down than if I stood up straight. Most of them said that I would. Hmmmmm. They needed proof.

So.....

Today I actually brought in a bathroom scale and weighed myself...that's right...in front of my students. I stood up straight, I crouched down into a ball, I stood on one leg. They were surprised to discover that I weighed the same no matter what position I stood. Finally! They began to understand that an object (like me) did not change mass or weight just because it changes shape.

Unfortunately, now my students all know how much I weigh...and I am sure that by tomorrow so will half the parents! Oh well, all in the name of science education!