Unit 3, Lesson 9
Differences of Fractions
Grade 4
Preparation
Lesson Narrative
Previously, students decomposed fractions into sums of other fractions and wrote equations to record the decompositions. They also used number lines to reason about addition of fractions with the same denominator. In this lesson, students use number lines to think about differences of fractions with the same denominator. They also practice reasoning about equivalence and decomposing fractions (including mixed numbers) mentally to facilitate subtraction.
As in earlier grades, students may think about subtraction as taking away a number from another number, or as finding an unknown addend. The way they represent differences of fractions on a number line may vary accordingly.
- Engagement
- MLR8
- Explain (orally) strategies for using a number-line diagram to subtract fractions.
- Interpret (orally) number-line diagrams that represent a subtraction strategy.
- Let’s explore differences of fractions on a number line.
Required Preparation
- Create a set of cards from the blackline master for each group of 2 students.
Teacher Reflection Questions
Based on students’ work today, what did you learn about their understanding of the relationships between addition and subtraction? How will you use these insights to prepare for upcoming work?