Tabletop Trickery
This puzzle is a powerful optical illusion that persists in seeming impossible, even when you prove that it’s not. A variation of this illusion appeared in the April 1998 Physics Teacher magazine, and is credited to Martin Gardner, the noted puzzle-creator. It consists of two seemingly very different tables that turn out to have congruent tops. Our version of this puzzle pictures a room full of tables, and the challenge is to find the two that have congruent tops.
Get Puzzle (116k PDF file; Requires Adobe Reader)