Measuring Angles

Learning Resource Type

Lesson Plan

Subject Area

Mathematics

Grade(s)

Overview

This lesson is designed to teach students to measure angles with a protractor. The student will be taught how to read the protractor correctly by using either the top or bottom set of numbers. The lesson will reinforce classifying angles as acute, right, and obtuse. The student will sketch angles given a specified measure.

This lesson results from the ALEX Resource Gap Project.

Mathematics (2019) Grade(s): 4

MA19.4.25
Use a protractor to measure angles in whole-number degrees and sketch angles of specified measure.

Vocabulary

Protractor
Angle
Whole number
Degree
Center
Circle
Intersect
Arc
Point
Ray
One-degree angle
Vertex

Knowledge

Students know:

Measurable attributes of geometric shapes, specifically angle size.
Units of measurement, specifically one-degree angle (degrees).
An angle is measured by the number or iterations of one-degree angles that exactly cover the rotation of the angle.

Skills

Students are able to:

Sketch angles given a specified measure.
Use appropriate tools to find angle measure.

Understanding

Students understand that:

the rotation of an angle is measured by the number of one-degree angles that exactly cover the rotation of the angle.

Primary Learning Objectives

The student will be able to measure angles to the nearest whole number degree using a protractor.

The student will be able to sketch an angle from a specified measure.

Additional Learning Objective(s)

The student will be able to classify angles by its measure.

Procedures/Activities

Before:

Write on the interactive whiteboard the following: Angle, Acute Angle, Obtuse Angle, and Right Angle.
The teacher will ask the students to stand by their desks and model each term with their arms. The teacher will model first.
1. Angle – the arms will make a V.
2. Right Angle – the arms will make an L.
3. Acute Angle – the arms will make a V.
4. Obtuse Angle – the arms will make a wide V.
5. The teacher will mix up the terms and repeat.

During:

The teacher will hold up a protractor and tell the students that this is the instrument to measure an angle. The teacher will pass out the protractors. The protractor has two rows of numbers from 0 to 180.
The teacher will explain the parts of the protractor.
1. The hole in the middle of the ruler part is for the point (vertex) of the angle.
2. The numbers from 0 to 180 on top are for the angle with the opening on the left (>).
3. The numbers from 0 to 180 on the bottom are for the angle with the opening on the right (<).
4. The teacher will tell the students to draw an angle with the opening on the left (>). Model this on the interactive whiteboard.
5. The teacher will show the students how to place the vertex in the right place and line up the 0 on the left side of the protractor.
6. The teacher will then follow the other leg (ray) of the angle to show the measure on the protractor. The teacher will write the number and then show the students that the small 0 at the top of the number is the symbol for degrees.
7. The teacher will tell the students that if the legs (rays) are not long enough, then they can extend the legs with the ruler part of the protractor.
8. The teacher will tell the students to draw an angle that opens to the right (<). The teacher will show the students how to use the numbers on the bottom.
9. The teacher will do a guided practice with the worksheet called https://www.mathworksheets4kids.com/angles/measuring/standard-type1-easy1.pdf. The students can work with partners. The teacher will monitor engagement and do an informal assessment. The intervention will be to do one-on-one differentiated instruction.

After:

The teacher will hand out the formal assessment called Measuring Angles in the attachment section. The accelerated students will be assigned the worksheet, https://www.mathworksheets4kids.com/angles/measuring/multiple-rays1.pdf.

Assessment Strategies

Informal:

The teacher will monitor the students as they measure angles in the group activity, making sure that all students are measuring the angles accurately with the protractors.

Formal:

The teacher will use the worksheet called Measuring Angles in the attachment section to make sure all students have mastered measuring angles with a protractor.

Acceleration

The accelerated students will be assigned the worksheet, https://www.mathworksheets4kids.com/angles/measuring/multiple-rays1.pdf.

Intervention

Struggling students may need one-on-one instruction in a small group and use the following website: (click on the step by step button) http://studyjams.scholastic.com/studyjams/jams/math/geometry/measure-angles.htm.

Total Duration

61 to 90 Minutes

Background/Preparation

Teacher:

The teacher needs to have taught the students how to recognize the different types of angles using pattern blocks. The teacher needs to have enough protractors for all the students. The teacher will need to practice using the protractor tool on the interactive whiteboard. This is an introductory lesson for measuring angles.

Student:

The student should know the parts of an angle. The student needs to know the following terms: vertex, rays, acute, obtuse, right, and straight.

Materials and Resources

Class set of protractors

Notebook

Pencil

Worksheet from the website https://www.mathworksheets4kids.com/angles/measuring/standard-type1-easy1.pdf (copy for all students)

Measuring Angles worksheet in the attachment section

Worksheet for Accelerated Students: Make copies as needed

https://www.mathworksheets4kids.com/angles/measuring/multiple-rays1.pdf

Computer, laptop, or iPad (use with intervention website)

Intervention Website: (click on the step by step button)

http://studyjams.scholastic.com/studyjams/jams/math/geometry/measure-angles.htm

Technology Resources Needed

Desktop computer with access to interactive whiteboard