# Lesson 12

Sumas y diferencias de fracciones

### Lesson Purpose

### Lesson Narrative

Previously, students learned to decompose mixed numbers and write equivalent fractions for whole numbers to add and subtract fractions. In this lesson, they practice finding the value of sums and differences of fractions while also taking a closer look at their reasoning strategies. In the first activity, students complete addition and subtraction equations, each with a missing number. They then reflect on the steps they took and consider why they found certain ways of reasoning more productive than others. In the second activity, students examine and explain when it might be useful to decompose numbers when finding sums and differences of fractions. In explaining their answers and strategies, students need to be precise in their word choice and use of language (MP6).

- Action and Expression

- MLR8

### Learning Goals

Teacher Facing

- Add and subtract fractions (including mixed numbers) with the same denominator.
- Analyze strategies for reasoning about sums and differences of fractions with the same denominator.

### Student Facing

- Sumemos y restemos fracciones, y analicemos nuestras estrategias.

### Required Preparation

### CCSS Standards

Addressing

### Lesson Timeline

Warm-up | 10 min |

Activity 1 | 20 min |

Activity 2 | 15 min |

Lesson Synthesis | 10 min |

Cool-down | 5 min |

### Teacher Reflection Questions

### Suggested Centers

- Compare (1–5), Stage 6: Add and Subtract Fractions (Addressing)
- Rolling for Fractions (3–5), Stage 2: Multiply a Fraction by a Whole Number (Addressing)
- Creating Line Plots (2–5), Stage 2: Quarter Inches (Supporting)