I have a challenge for you. Fill a glass of water right up to the top. Guess how many paper clips can you put into the glass before the water spills over. Will it be 5 or 10? Does it matter if you slide them in or if plop them in? Keep filling the glass with paper clips - the girls scouts just did this and were able to add a whole lot.
Refill the glass and see you can float a paper clip on the top of the water. It is far trickier than you'd think. If you really get stuck, use a fork to lower it down onto the surface.
Check out the pictures here.