Finding the Measurement of an Unknown Angle by Adding & Subtracting: 4th Grade Lesson

Solve addition and subtraction problems to find unknown angles. Scroll to the bottom of the article for the downloads.

Lesson Objective: The lesson is aligned to the Common Core State Standards for Mathematics – 4MD.7 Geometric Measurement – Recognize angle measure as additive.

Materials Required: Calculator

Lesson Procedure:

Identifying Measurement of an Angle using Addition and Subtraction

Use addition to find the angle measurement in degrees.

1. Find the measurement of angle a.

2. Find the measure of angle b.

3. Find the measure of angle c. 

4. Find the measure of angle d.


Download a copy of the group work as well as an individual assignment for students. Includes answers.

Download an Assessment on Measuring Angles.

Students should be able to recognize when an angle is decomposed into non-overlapping parts, the angle measure of the whole is the sum of the angle measures of the parts. Students should be able to find the angle measure in degrees using addition or subtraction.

This post is part of the series: Finding the Measurement of Angles: 4th Grade Lessons

These three lessons will have students learn to find the measurement of angles by using protractors, addition and subtraction. These math lessons all meet Common Core objectives.
  1. Finding Measurement of Angles: 4th Grade Lesson
  2. Finding the Measurement of Angles using a Protractor: 4th Grade Lesson
  3. Finding Measurement of Angles through Addition and Subtraction: 4th Grade Lesson