Lesson Plan: Areas of Similar Polygons Mathematics

This lesson plan includes the objectives, prerequisites, and exclusions of the lesson teaching students how to calculate areas of similar polygons given two corresponding side lengths or the scale factor between them and the area of one of the polygons.

Objectives

Students will be able to

• recall the relationship between the length scale factor and the area scale factor; that is, that the area scale factor is the square of the length scale factor,
• calculate the area of a similar polygon given two corresponding lengths and the area (or the means to calculate the area) of one of the two shapes (or vice versa),
• write the ratio of the areas of two similar polygons given the ratio between their lengths,
• calculate the areas of similar polygons using scale factors, along with relevant information such as the perimeters of the two shapes,
• solve multistep problems involving areas of similar polygons.

Prerequisites

Students should already be familiar with

• properties of similar shapes,
• proportions, scale factors, similarity, and related calculations.

Exclusions

Students will not cover

• the similarity of circles,
• volume scale factors.