 Measuring angles with a protractor

# Measuring angles with a protractor

I can measure angles in whole-number degrees using a protractor.

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## General

Students will recognize angles as being straight or right and measurements for those angles will be discussed as benchmark numbers. Throughout the lesson, students will discuss angles in terms of being acute or obtuse (bigger or less than a right angle) and practice classifying angles. They will also use benchmark numbers to pick an appropriate measurement for a given angle. Finally, students will be instructed to measure angles with a protractor.

## Standards

CCSS.MATH.CONTENT.4.MD.C.6
CCSS.MATH.CONTENT.4.G.A.1

## Learning Objective

Students will be able to use a protractor to measure angles in whole-number degrees and sketch angles of specified measure.

## Introduction

Students look at different pictures of people and try to guess their ages. Use this conversation to introduce benchmark numbers, numbers in multiples of tens or fives. Then discuss benchmark angles that can help estimate angle measurements.

## Instruction

Review "right angles" and guide students through estimating angle measurements with benchmark measurements. Go over straight angles and review acute angles, obtuse angles, and the vertex. Define and discuss these terms. Have students look at different angles, and choose the correct measurement of the angle by determining first if the angle is acute or obtuse. After this, watch the video that explains how to use a protractor to measure angles. Show students the protractor on the board, and go through the different parts of the protractor. Finally, have students use a transparent protractor on the board to measure the angles displayed. There is a printable worksheet included for this practice activity.

## Quiz

Students respond to ten multiple-choice and fill-in responses.

## Closing

Students will sketch an angle and have a classmate measure it. You can watch the video to learn how to draw an angle using a protractor. 