Changing Lengths

The magician shows three ropes of equal length, he then balls up all three ropes and the come out to be three different lengths.

Start with three ropes of the lengths 1, 2, and 3 feet. Take the 1 foot rope and loop it around the 3 foot rope and hold all three ropes together with your thumb covering where the 1 foot and 3 foot ropes are looped together. It will appear as though all three ropes are the same length, so all you have to do is ball up the ropes and remove them from your hand one by one to show that the lengths are no longer equal.