A couple of days ago, I was helping my son clean out his closet and sort out old toys that he has long-since outgrown. In this process we came across something that I can only describe as a mass of string intertwined with a ball, a hand-made paper medal and an expensive, portable insect observatory. When we first saw this tangled knot of twine, my son exclaimed, "My ball! I was looking for this!" It was a ball that he himself had constructed with an elastic string attached which caused the ball to immediately bounce back to the thrower. In his enthusiasm, he began to try to untie the mess.