# Lesson Plan: The Sum of Angles in Quadrilaterals Mathematics

This lesson plan includes the objectives, prerequisites, and exclusions of the lesson teaching students how to find a missing angle’s measure in a quadrilateral knowing that the sum of angles in a quadrilateral is 360 degrees.

#### Objectives

Students will be able to

- understand that the sum of the interior angles in a convex quadrilateral is 360 degrees,
- use the fact that the sum of the interior angles in a convex quadrilateral is 360 degrees to find a missing angle measure in a given quadrilateral,
- construct and solve an algebraic equation to find a missing angle measure in a given quadrilateral,
- use angle facts to find a missing angle measure in a quadrilateral that appears within a more complex geometric diagram.

#### Prerequisites

Students should already be familiar with

- naming and classifying different types of quadrilaterals,
- constructing and solving simple algebraic equations,
- angle facts.

#### Exclusions

Students will not cover

- concave quadrilaterals,
- the general formula for the sum of the interior angles of a convex polygon,
- radians.