# 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

Building On

Addressing

### 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)

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