Lesson 9
Use Equivalent Expressions
Lesson Purpose
Lesson Narrative
In a previous lesson, students saw that having a common denominator is useful for adding or subtracting fractions. In this lesson students add and subtract fractions using equivalent expressions where the fractions have the same denominator. Students work with denominators where one is a multiple of the other so they only need to change the denominator in one of the 2 fractions. In each case the numerators are chosen so that either denominator works as a common denominator and students compare different strategies for finding the sum or difference.
 Action and Expression
 MLR8
Learning Goals
Teacher Facing
 Use equivalent expressions to add and subtract fractions with unlike denominators.
Student Facing
 Let’s use equivalent expressions to add and subtract fractions with unlike denominators.
Required Preparation
Lesson Timeline
Warmup  10 min 
Activity 1  15 min 
Activity 2  15 min 
Activity 3  10 min 
Lesson Synthesis  10 min 
Cooldown  5 min 
Teacher Reflection Questions
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)
Print Formatted Materials
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