Why do round objects hit the ground at the same time when dropped at the same time?

If you are teaching physical science and have often tried to come up with a great explanation about why objects hit the ground at the same time if they are dropped from the same height and time, then this video does an excellent job with this explanation  The video first starts off people off the street being asked about which ball will hit the ground at the same time.  After listening to their ideas he then performs the experiment.  He takes it one step further when he asks the people why they think both objects hit at the same time.  Some of their scientific ideas are pretty funny to listen to.  Try showing this video to your students asking them questions along the way.  Or even better yet try the experiment with them, adding different sized and weighted objects.