Drop two objects of different mass, say a bowling ball and a golf ball, from a high building. Which hits the ground first?
The answer? They hit at the same time. The more massive object has more stuff for gravity to act on, but because it's more massive, it also takes more to get it to move. The less massive object has less "stuff" for gravity to act on, but is easier to move. The end result is they fall at the same rate.
This seems hard to believe. Heavier things just seem like they should fall faster. That may be partly due to the fact that we can't test it easily; you don't really want to drop heavy things off of buildings just out of curiosity.
Okay, so why not do what Galileo did when he first demonstrated this fact? Use a ramp instead of a building.
Start your bowling ball and your golf ball at the same spot on the ramp and let go at the same time. If our intuitive sense of this situation is right, and heavier things fall faster than lighter ones, then they should also roll faster. Putting them on a ramp only slows things down so it's easier to watch.
Try this yourself, however, and you will see that the two roll at exactly the same rate. That is, both will roll faster and faster as they proceed down the ramp, but they will keep pace with each other and hit bottom at the same moment.
Congratulations! You have demonstrated that all things fall at the same rate.