This document provides a lesson on calculating the perimeters of polygons. It begins by defining a polygon and perimeter. Students are shown how to calculate the perimeter of a rectangle by adding the length and width measurements. The formula for a rectangle's perimeter, 2 x length + 2 x width, is introduced. Other shapes where not all side measurements are needed, like squares, are discussed. Finally, students are given a challenge to calculate the perimeter of a more complex shape and express it in words and letters.