In our Physical Science class, 3rd ESO, we were wondering what the value of Earth's gravity was. We decided to drop some tennis balls from the stairs of our school, at different heights, and measure the time they took to reach the floor. By using a set of very complicated formulas, calculations, and graphs that only smart scientists like us are able to understand, we reached the conclusion that gravity is 9.8 m/s2 approximately.

We had lots of fun trying to skip the falling balls so they could hit the floor conveniently. Now we plan on going to the Moon and repeat the experiment to see if what the books say about Moon's gravity being smaller than Earth's is actually true.