I started to post this in the homework area but it is a square peg and that is a round hole. My son (6th grade) wanted to observe what would happen when he dropped a marble and a penny into 8inches of water from 20inches above the water and .5 inches above the water. With the marble he found that it traveled through the water about twice as fast when dropped from the higher level. The penny though was about 20 % faster from on high. Bottom line is he is having hard time understanding what forces are at work here and how he can explain it to other 6th grade students. Any help breaking this down in layman's terms would be appreciated.