Lesson 14
Reasoning about Angles (Part 1)
Lesson Purpose
The purpose of this lesson is twofold: for students to use known angles to reason about unknown angles on a clock, and for them to practice drawing angles of given measurements.
Lesson Narrative
Angles are ever present on an analog clock. In this lesson, students investigate and solve problems about the angles formed by a clock’s hour and minute hands. Students reason about the number of degrees between the two hands or the number of degrees the minute hand has turned over some specified time. To do so, students rely on their understanding of fractional parts (for example, a round clock can be divided into 12 and 60 equal parts), their ability to tell time and elapsed time, and their knowledge of angle types and measurements.
- Engagement
- MLR8
Activity 2: Tick Tock
Learning Goals
Teacher Facing
- Draw angles of given measurements.
- Reason about angle measurements within a circle.
Student Facing
- Let’s find the size of angles on the clock.
Required Materials
Materials to Gather
Required Preparation
Lesson Timeline
| Warm-up | 10 min |
| Activity 1 | 15 min |
| Activity 2 | 20 min |
| Lesson Synthesis | 10 min |
| Cool-down | 5 min |
Teacher Reflection Questions
How did students’ understandings about time—how to tell time and find elapsed time—help their work with angles on the clock?
Suggested Centers
- Which One? (K–5), Stage 4: Grade 3 Shapes (Supporting)
- Can You Draw It? (1–5), Stage 4: Area and Perimeter (Supporting)