This is a short song to help learn the difference between the different types of triangles.
Grover and Rosita illustrate and explain the properties of a triangle. Rosita brings over two different-looking triangles to serve as visual aids, and Grover does not consider them to be triangles. He creates an equilateral triangle and states why it is a triangle. Rosita mentions that the triangles she brought in fit his definition of a triangle, causing Grover to realize that there are different types of triangles.
The Bad Man explains more about the three triangles.
The Sad Man and the kids look at the different types of triangles.
Homer enters a bathroom and happens upon some glasses. He wears them, and in an attempt to be smart, incorrectly recites the pythagorean theorem. Someone in one of the bathroom stalls corrects his mistake.