Sesame Street: Different Looking 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.