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# Summary

This lesson is designed to help students build a visual understanding of different angle sizes. If students go through the experience of making their own protractor with modular parts than they'll improve their ability to estimate and measure angles. This projects includes a sample modular protractor but the goal is to show students how to make one for themselves.

# Print Settings

**Printer Brand: **

MakerBot

**Printer: **

**Rafts: **

Yes

**Supports: **

No

**Resolution: **

0.3

**Infill: **

10%

**Notes: **

These are pretty easy to print. The 180 degree model will require supports depending upon how you print it.

# Standards

# Overview and Background

Protractors can be tough for students to understand mainly because the markings go in both directions. With this modular protractor you can have students use one angle measure at a time. Then the different angles can be combined to equal bigger angles. This will greatly improve their ability to estimate angles and subsequently improve their ability to measure angles using a protractor. Imagine a student know that the angle they are measuring is 120 degrees and not 60 because they remember that the 120 degree was bigger.

**Overview and Background**

Student will learn how to estimate and measure the size of angles by using a modular protractor and later they'll make their own.

**Objectives**

Students will be able to estimate and measure angles.

**Standards**

Geometric measurement: understand concepts of angle and measure angles.

*CCSS.MATH.CONTENT.4.MD.C.5*

Recognize angles as geometric shapes that are formed wherever two rays share a common endpoint, and understand concepts of angle measurement:

*CCSS.MATH.CONTENT.4.MD.C.5.A*

An angle is measured with reference to a circle with its center at the common endpoint of the rays, by considering the fraction of the circular arc between the points where the two rays intersect the circle. An angle that turns through 1/360 of a circle is called a "one-degree angle," and can be used to measure angles.

*CCSS.MATH.CONTENT.4.MD.C.5.B*

An angle that turns through n one-degree angles is said to have an angle measure of n degrees.

*CCSS.MATH.CONTENT.4.MD.C.6*

Measure angles in whole-number degrees using a protractor. Sketch angles of specified measure.

*CCSS.MATH.CONTENT.4.MD.C.7*

Recognize angle measure as additive. 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. Solve addition and subtraction problems to find unknown angles on a diagram in real world and mathematical problems, e.g., by using an equation with a symbol for the unknown angle measure.

# Lesson Plan and Activity

After you have students use the protractor teach them to make their own. Using Tinkercad.com this can be done easily using the built in protractor.

Step 1

Start on a blank work plane and drag over a red square from the shapes toolbar.

Step 2

Make the square into a thinner stick

Step 3

Select the stick and copy->paste the shape and don't move it.

Step 4

Click on the double headed arrow and you can rotate it. the protractor will appear and a student can rotate the shape and reach the desired angle. Make sure to observe the direction in which you teach the students to rotate the stick.

Step 5

Drag over a hole square and remove the excess from the two sticks. You should have a shape with the desired angle.

Step 6

Now drag over some number from the text toolbar and label the angle. I use an "O" and shrink it to represent the degree symbol.

Step 7

Select all the shapes and group them. Make sure all the shapes are touching.

Now you can use this process to make several different angles. There are different ways of joining the pieces so I'll leave that up to you.

You can use this with many of the already available online worksheets and other resiurces. I've even had my student use this in the computer lab and they just hold up the model to the screen. It works great with code.org courses where they need to measure the degrees of a turn.

# Duration of Lesson

2-3 classes

# Preparation

I would start with some review of angle concepts and maybe make a few worksheets to have some pre-assessment information.

**This website has a variety of worksheets that are common core aligned:**

http://www.commoncoresheets.com/Angles.php

**This website is good for a visual understanding of angles:**

http://www.homeschoolmath.net/teaching/g/measure_angles.php

**This website is great for exit quizzes:**

www.thatquiz.org