# Lesson 13

Find Angle Measurements

### Lesson Purpose

### Lesson Narrative

In this lesson, students use tactile tools to find angle measurements and observe more clearly that angles are additive. They compose and decompose angles by arranging paper cutouts, by folding paper or tracing, and by drawing diagrams. Students arrange smaller angles whose sizes are unknown into larger angles with familiar sizes and features (\(90^\circ\), \(180^\circ\), and \(360^\circ\)). Once the measurement of an angle is known, they use it to find those of other angles. For example, if two copies of angle \(x\) form a right angle, angle \(x\) must be \(45^\circ\). If another angle, \(z\), can be decomposed into three of these \(45^\circ\) angles, then \(z\) must be \(135^\circ\).

Encourage students to continue to collect, define, and illustrate new terms to support communication and reasoning at the end of each lesson.

- Representation

### Learning Goals

Teacher Facing

- Compose and decompose angles to determine their measurements.

### Student Facing

- Let’s compose and decompose angles to find their measurements.

### Required Materials

### Required Preparation

Activity 1:

- Create 4 copies of each angle (\(p\), \(q\), \(r\), and \(s\)) from the blackline master for each group of 2–4 students.
- Cut out the angles in advance, or prepare scissors and extra time for students to cut out the angles.
- If using patty paper instead of cutouts of the angles, each student needs 1–2 sheets of patty paper.

### CCSS Standards

Addressing

### Lesson Timeline

Warm-up | 10 min |

Activity 1 | 25 min |

Activity 2 | 10 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)

### Print Formatted Materials

Teachers with a valid work email address can click here to register or sign in for free access to Cool Down, Teacher Guide, and PowerPoint materials.

Student Task Statements | docx | |

Lesson Cover Page | docx | |

Cool Down | Log In | |

Teacher Guide | Log In | |

Teacher Presentation Materials | docx | |

Blackline Masters | zip |