Lesson 20
Will it Always Work? (optional)
Lesson Purpose
The purpose of this lesson is for students to explain how the product of two numbers compares to one factor based on the size of the other factor.
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 the comparisons and describe in general how to make comparisons using a strategy that makes sense to them. No representation is provided or suggested so this gives students an opportunity to think about the different methods they have learned, namely calculation, number lines and the distributive property, and choose the one that makes sense in each situation.
 Representation
 MLR1
Learning Goals
Teacher Facing
 Make generalizations about multiplying a whole number by a fraction greater than, less than, or equal to 1.
Student Facing
 Let’s make generalizations about multiplying a whole number by a fraction.
Required Materials
Materials to Gather
Required Preparation
CCSS Standards
Addressing
Lesson Timeline
Warmup  10 min 
Activity 1  20 min 
Activity 2  15 min 
Lesson Synthesis  10 min 
Cooldown  5 min 
Teacher Reflection Questions
What questions did you ask today that helped students reason about the size of a product without performing multiplication?
Suggested Centers
 Rectangle Rumble (3–5), Stage 5: Fraction Factors (Addressing)
 Rolling for Fractions (3–5), Stage 4: Multiply Fractions (Supporting)
Print Formatted Materials
For access, consult one of our IM Certified Partners.
Additional Resources
Google Slides  For access, consult one of our IM Certified Partners. 

PowerPoint Slides  For access, consult one of our IM Certified Partners. 