So, what would happen if you dropped a hammer and a feather at the same time, from the same height? Well, the hammer would hit the ground first, right? But why? You might think it's because the hammer is heavier, or has more mass than the feather. But it's actually not because of that at all. In this episode of Crash Course Kids, Sabrina shows us that the rate at which things fall to Earth has to do with something called air resistance... oh, and we take a trip to the moon.