Lesson 9
Relate Area to Multiplication
Lesson Purpose
Lesson Narrative
Students build on their understanding of multiplication and area from grade 3 as they work with areas with fractional side lengths. Students may count the number of smaller parts within a rectangle and will need to recognize and consider the size of these parts, which is a fraction of a square unit. It is important to be precise in the units used to describe the area and teachers should make sure to refer to “square units” rather than “squares.”
As with the area work in grade 3, the commutative property may come up. The commutative property allows students to find products in a way that makes sense to them. For example a student might find the area of a rectangle with side lengths \(\frac{1}{2}\) and 4 by thinking of 4 groups of \(\frac{1}{2}\).
In Unit 6, students have another opportunity to interpret the product of a fraction and a whole number in the context of multiplication as scaling. This section is about area.
 Action and Expression
 MLR8
Learning Goals
Teacher Facing
 Find the area of a rectangle with a unit fraction side length in a way that makes sense to them.
Student Facing
 Let’s explore the area of rectangles with one side length that is a unit fraction.
Required Materials
Materials to Copy
 Grid Paper 5
Required Preparation
CCSS Standards
Addressing
Lesson Timeline
Warmup  10 min 
Activity 1  15 min 
Activity 2  20 min 
Lesson Synthesis  10 min 
Cooldown  5 min 
Teacher Reflection Questions
Suggested Centers
 Target Measurements (2–5), Stage 5: Fractions of Angles (Addressing)
 How Close? (1–5), Stage 6: Multiply to 3,000 (Supporting)
Print Formatted Materials
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Additional Resources
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