In calculus class, the teacher outlined a problem with two yards of specific sorts of shapes, the idea being to enclose the maximum area with a given amount of fence. After a while, he asked what areas people had gotten. Mine was more, so I said so. He said I had the wrong answer. I maintained that my answer was correct, and I could prove it. Sure enough, he called me up to the board to show everybody. I started by drawing the diagram – with the two yards sharing a section of fence. As soon as I drew that, he knew what I had done. He pointed out that no-one had attempted that approach in all the years he had taught the class. He also pointed out that the problem was much harder to solve that way. Heh heh heh.