Topics
9. Shapes and angles
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United States of AmericaUT
Grade 4

9.06 Measure and compare angles

Lesson
Practice
Lesson

Are you ready?

Do you remember how to estimate angles?

Which angle is greater than $180$180 degrees? 

  1. A

    B

    C

Learn

Let's see how we can compare two angles of a skateboard ramp!

 

Apply

question 1

Which of these angles is larger?

  1. A

    B

 

Learn

We can measure the exact angle, using a special tool called a protractor. Let's see how to use one.

Apply

Question 2

What is the angle being measured by this protractor?

  1. $\editable{}$ degrees

 

Remember!

A protractor is an instrument that allows us to measure an angle. Start with one arm of the angle on the $0^\circ$0° line and read the amount of turn required to reach the second arm.

Outcomes

4.MD.5

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

4.MD.5.a

Understand that 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 other angles.

4.MD.5.b

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

4.MD.6

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

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