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9. Shapes and angles
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United States of AmericaUT
Grade 4

9.04 Right angles

Lesson
Practice
Lesson

Are you ready?

Do you remember what the measure of an angle represents? Let's try this problem to review. 

How many $1^\circ$1° angles fit into a full circle?

Learn

Let's learn about right angles and how we can compare other angles to them.

Apply

Question 1

A right angle is a:

  1. Quarter turn

    A

    Half turn

    B

Question 2

Which of the following is a right angle?

  1. A

    B

Remember!

A right angle is exactly $90^\circ$90°.

 

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.

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