- What benchmark angles did we use to estimate angle measures? (the straight angle 180°, right angle 90°, and full turn 360°)
If you have not done so, refine the class definitions of these words by adding degree measures and pictures of these angles to the Geometry Word Chart.
- What tool did we use to measure angles? (protractor)
Ask each student pair to trace their protractor on a blank sheet of paper and then add notes showing what they need to know about a protractor to measure angles. Students might:
- Add notes like Luis did above Question 8 in the Student Guide.
- Include their steps for using their estimate as a first step to understanding the markings on the protractor.
- Explain how to measure a reflex angle using a protractor.
Summarize students' ideas by creating a class version on chart paper. This should remain displayed as part of the Geometry Word Chart.
Assign Check-In: Questions 8–16 in the Student Activity Book.
Use Check-In: Questions 8–16 on the Draw and Solve Problems with Angles pages in the Student Activity Book to assess students' abilities to estimate the size of an angle using benchmarks [E11] and use a protractor to measure angles to the nearest degree [E12]. Look for the following things while you are evaluating student work:
- Did students describe the benchmarks they used in their estimates?
- Did students use their estimates to decide which numbers to use on the protractor?
- Did students compare their measurements and estimates to check for reasonableness?
Assess the following Math Practices Expectations as well:
- MPE3.
- Check for reasonableness. I look back at my solution to see if my answer makes sense. If it does not, I try again.
- MPE6.
- Use labels. I use labels to show what numbers mean.
The Workshop in Lesson 6 provides targeted practice with estimating angle size using 90°, 180°, and 360° as benchmarks [E11].
