Lesson 20
How Much in the Group? (optional)
Lesson Purpose
Lesson Narrative
In this optional lesson, students solve problems where a whole number quantity is a unit fraction of an unknown whole number. In these situations students may rely on their understanding of the relationship between multiplication and division. For example, if 8 ounces is \(\frac{1}{4}\) of the amount of water in a bottle, students might represent this with a tape diagram:
The tape diagram suggests the equation \(8 = \frac{1}{4} \times {?}\) which students will likely solve by seeing that \({?} = 4 \times 8\). The equation \(8 = \frac{1}{4} \times {?}\) can also be written using division with the equation \({?} \div 4 = 8\).
 Engagement
 MLR8
Learning Goals
Teacher Facing
 Represent and solve problems involving division of a whole number by a unit fraction.
Student Facing
 Let’s solve more problems involving multiplication and division with fractions.
Required Preparation
CCSS Standards
Addressing
Lesson Timeline
Warmup  10 min 
Activity 1  20 min 
Activity 2  10 min 
Activity 3  10 min 
Lesson Synthesis  10 min 
Cooldown  5 min 
Teacher Reflection Questions
Suggested Centers
 How Close? (1–5), Stage 6: Multiply to 3,000 (Addressing)
 Rolling for Fractions (3–5), Stage 5: Divide Unit Fractions and Whole Numbers (Addressing)
Print Formatted Materials
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Additional Resources
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