Lesson 3

Turning Through Angles

Est. Class Sessions: 1–2

Developing the Lesson

Part 2. Angles and Degrees

Read the vignette in the Angles and Degrees section of the Student Guide with the class. Draw the angle shown on Mrs. Dewey's board on the Geometry Word Chart. Ask a student to label the vertex and arc shown in the picture.

Have students answer Questions 6 and 7 with a partner. Discuss students' responses with the whole class. See Content Note.

Ask:

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  • Are Mrs. Dewey's and Maya's angles the same size? (no)
  • Make a white angle the same size as Mrs. Dewey's angle with your Angle Circle. Using a word from our Geometry Word Chart, describe this angle. (acute, because it is less than 45 degrees)
  • Make a white angle the same size as Maya's angle with your Angle Circle. What word would you use to describe Maya's angle? (A reflex angle because it is more than a straight angle, but not the full circle.)
  • How are the angles related? (The angles share the same vertex and rays. When I make Maya's angle with white, I see Mrs. Dewey's angle is the green one. Added together, they make a full rotation around a circle.)

Continue reading with the class in the Student Guide about degrees as a measure of angle rotation. Students work with partners to answer Questions 8–10. In these questions, students find the degree measures of benchmark angles, including 90°, 180°, and 270°. Encourage students to use mental math to compute the degree measures for these angles. They may use calculators if needed.

Write the word “degree” on the Geometry Word Chart. Ask students to use words and pictures to represent the meaning of degree or degrees. Make sure the symbol for degrees (°) is included on the chart. Allow the class to discuss and refine the representations shown.

Student Guide: 382 383
Answers
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Student Activity Book:
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