1. Lesson 5-11 Unit Iteration for Angles
Overview: Students are introduced to the degree as a unit to measure angles.
Vocabulary: degree, straight angle, reflex angle

2. Begin With The End in Mind
You are introduced to ”degree ()”as a unit of measure.

3. Math Message
Keon used purple wedges to measure an angle. Latitia measured the same angle using light green wedges. Keon said the angle’s measurement was 5 wedges. Latitia said the angle’s measurement was 6 wedges. Who is correct? How do you know?

4. Math Message – Follow - Up
Share your answers.
We must have a “standard unit of measure.”
Name some standard units of measure in the U.S. Customary and metric system.

5. Math Message – Follow - Up
The standard unit of measure for angles is called a degree.
A degree () is the measure of a very small angle.
Angle measurements can be written using the word (1 degree) or the symbol (1).

6. Make a list of some things that are about the size of an angle measuring 1
If you were to iterate the angle measuring 1 all the way around the circle …, it would equal , or a full circle.

7. 360
270
90
180

8. ¼ turn = 90

9. A ½ turn is referred to as a straight angle (180º).

10. ¾ turn = 3 * 90 = 270
Note: An angle with a measure greater than 180º is called a reflex angle.

11. 4 4 turn = 4 * 90 = 360

12. Let’s use the clocks.
Start at 3:00 and 𝟏 𝟒 turn. What type of angle is this? What is the measurement in degrees of a quarter-turn?
Start at 3:00 again. Make a 𝟏 𝟐 turn. What type of angle is this? What is the measurement in degrees of a half-turn?
Start at 3:00 again. Make a 𝟑 𝟒 turn. What type of angle is this? What is the measurement in degrees of a three quarter turn?
Start at 3:00 again. Make a full turn. What type of angle is this? What is the measurement in degrees of a three quarter turn?

13. Review of Angles A right angle measures “exactly” 90º
An acute angle measures less than 90º
An obtuse angle measures greater than 90º and less than 180º
A “reflex” angle measures greater than 180º and less than 360º

14. Use your “benchmark” angles (e. g
Use your “benchmark” angles (e.g. 90, 180, 270) to estimate the measure of the angle.
Estimate the measure of this angle.

15. With a partner, complete page 183. (9 min)

16. Summary
How did you arrive at your “estimates” on math journal page 183?

17. Exit Ticket
Estimate the measure of this angle.
Notice the “arc.”