On Saturday, I was watching the Wizard of Oz. Towards the end of the movie, when the Scarecrow gets his brain, he exclaims, "The sum of the square roots of any two sides of an isosceles triangle is equal to the square root of the remaining side. Oh joy, rapture! I’ve got a brain!"
Well, the Scarecrow may have his brain, but he needs to go to math class and learn the Pythagorean Theorem.
I used to use this example when teaching. My original intention was to show the video clip and use the quote to help students learn the theorem.
Then I watched the clip. I had only vaguely remembered it and was so glad I reviewed it before showing it to the students. My lesson plans were immediately changed. I still showed the video, but instead of using it as an example, I asked the students to list all the things that were wrong with it. The students always came up with a pretty good list.
My advice to all teachers is to always review beforehand any media that you plan to use with students. I think this is usually done, but when time is short, you may want to skip this step. Don't!
My advice to students is to not believe everything in the movies, even when it sounds and seems like reasonable truth.
The actual Pythagorean Theorem states, "The sum of the squares of the lengths of the legs of a right triangle is equal to the square of the length of the hypotenuse.