# Lesson 8

Sumemos y restemos fracciones

### Lesson Purpose

The purpose of this lesson is for students to add fractions with unlike denominators in a way that makes sense to them.

### Lesson Narrative

In this lesson, students add and subtract fractions in a way that makes sense to them. They consider several important cases:

• The denominators of the two fractions are the same, which is review of work from a previous grade.
• One denominator is a multiple of the other so the fractions can be added by replacing only one of the fractions with an equivalent fraction.
• Neither denominator is a multiple of the other so a third new common denominator is needed to add the fractions.
Students describe how the situations are different and find the sums and differences in a way that makes sense to them. The denominators of the fractions used in this lesson are familiar from grade 3, inviting students to use a variety of different familiar representations.
• Action and Expression
• MLR8

Activity 2: Sumemos y restemos

### Learning Goals

Teacher Facing

• Add and subtract fractions with unlike denominators in a way that makes sense to them.

### Student Facing

• Sumemos y restemos fracciones.

### Required Materials

Materials to Copy

• Fraction Add and Subtract Sort

### Required Preparation

Activity 1:

• Create a set of cards from the blackline master for each group of 2.

### 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

Which students had opportunities to share their diagrams and thinking during whole-class discussion? How did you select these students?

### Suggested Centers

• Would You Rather? (2–5), Stage 3: Compare Units in a Given System (Addressing)
• Compare (1–5), Stage 6: Add and Subtract Fractions (Supporting)