Unit 6, Lesson 20
Will It Always Work? (Optional)
Grade 5
Preparation
Lesson Narrative
The goal of this optional lesson is to compare the size of a product to the size of one factor, applying what students have learned in the last several lessons. They make comparisons and describe in general how to make comparisons, using a strategy that makes sense to them. No representation is provided or suggested, which gives students an opportunity to think about the different methods they have learned, namely calculation, number lines, and the distributive property, and to choose the one that makes sense in each situation.
- Representation
- MLR1
- Generalize (orally and in writing) that $A \times B > B$ if $A > 1$, and $A \times B < B$ if $A < 1$, for any rational numbers $A$ and $B$.
- Let’s make generalizations about multiplying a whole number by a fraction.
Required Materials
Activity 2
Required Preparation
None
Teacher Reflection Questions
What questions did you ask today that helped students reason about the size of a product, without performing multiplication?