I am not sure who came up with this puzzle originally, but it is one that requires some lateral thinking to solve. And, yes, there is a solution, but please do not post it here as this puzzle is a good way to test your own way of thinking, and you cannot do that if you have the solution readily available.
Here, then, is the puzzle:
You are given twelve balls all of the same size and color. All but one are also of the same weight. The odd ball is either slightly lighter or slightly heavier than the other 11.
You are also given a balance scale. You are to find the odd ball and determine whether it lighter or heavier. You only have three weighings.