# Lesson 9

Usemos un transportador para medir ángulos

### Lesson Purpose

### 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 \(5^\circ\) or multiples of \(10^\circ\). In this lesson, students transition to measuring angles in units of \(1^\circ\).

Students then make sense of one-degree angles in terms of a fraction of a \(360^\circ\) turn and are introduced to the **protractor** as a tool of measurement. They make sense of the numbers on the tool and how \(1^\circ\) angles are shown. They learn to read the measurement of angles whose vertices 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 will further develop their ability to use a protractor by measuring a variety of angles with less support.

- Action and Expression

- MLR2

### Learning Goals

Teacher Facing

- Recognize that 1 degree is a measurement of a $\frac{1}{360}$ turn through a full circle.
- Use tools to measure angles.

### Student Facing

- Usemos algunas herramientas para medir ángulos.

### Required Materials

Materials to Gather

### Required Preparation

### CCSS Standards

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

### Suggested Centers

- Target Measurements (2–5), Stage 4: Degrees (Addressing)
- Compare (1–5), Stage 5: Fractions (Supporting)