Unit 7, Lesson 9
Use a Protractor to Measure Angles
Grade 4
Preparation
Lesson Narrative
Before this lesson, students have compared and measured angles, using informal tools (analog clocks) and reference angles, all of which were multiples of or multiples of . In this lesson, students transition to measuring angles in units of .
Students then make sense of one-degree angles in terms of a fraction of a turn, and are introduced to the protractor as a tool of measurement. They make sense of the numbers on the tool and how angles are shown. They learn to read the measurement of angles, the vertices of which have been pre-aligned to the center point of a protractor.
Students will continue to add new vocabulary to their personal word walls. In the next lesson, students further develop their ability to use a protractor by measuring a variety of angles, with less support.
- Action and Expression
- MLR2
- Describe (orally and in writing) that 1 degree is a $\frac{1}{360}$ turn through a full circle.
- Explain (orally) how to use a protractor to measure the size of an angle.
- Let’s use some tools to measure angles.
Required Materials
Activity 1
Required Preparation
None
Teacher Reflection Questions
The first two activities offered opportunities for students to take multiple solution paths. Were all unique perspectives or strategies heard? Which students were able to share their ideas? Which didn’t get a chance? How can their voices be added into the conversation tomorrow?