Unit 6, Lesson 8
Add and Subtract Fractions
Grade 5
Preparation
Lesson Purpose
The purpose of this lesson is for students to add and subtract fractions with unlike denominators in ways that make sense to them.
Lesson Narrative
In this lesson, students add and subtract fractions in ways that make 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 the differences in ways that make 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
- Explain (orally and in writing) strategies for adding and subtracting fractions with unlike denominators when one denominator is a multiple of the other.
- Let’s add and subtract fractions.
Required Preparation
Activity 1
- Create a set of cards from the blackline master for each group of 2.
Teacher Reflection Questions
Which students had opportunities to share their diagrams and their thinking during the whole-class discussion? How did you select these students?
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