When asked what shape "A" is, most students in second grade can tell you that it is a triangle. When asked what shape "B" is, some students get very confused. It does not look like shape "A" so it cannot be a triangle. This is when the definitions of the shapes come into play. We teach our students to go through the definition and see if the shape fits the definition, while always using proper terminology.
To practice knowing the definition of several polygons, we play shape games. Check out one of our favorites below.