Lesson 15
Find Missing Side Lengths
Lesson Purpose
The purpose of this lesson is for students to find missing side lengths of rectangles and rectangular prisms using their understanding of area, volume, and multidigit division.
Lesson Narrative
In an earlier unit, students learned to find the volume of rectangular prisms either by multiplying the length, width, and height or choosing a base and multiplying the area of that base by the corresponding height. In this unit, students learned to use division strategies to divide multidigit numbers. The purpose of this lesson is to use multiplication and division to solve problems about area and volume. Throughout, students apply multiplication and division and what they know about the relationship between the length, width, and height of a rectangular prism and its volume to solve problems (MP2).
 Engagement
 MLR8
Learning Goals
Teacher Facing
 Solve problems involving area and volume using the relationship between multiplication and division.
Student Facing
 Let’s use the relationship between multiplication and division to solve problems.
Required Preparation
Lesson Timeline
Warmup  10 min 
Activity 1  15 min 
Activity 2  20 min 
Lesson Synthesis  10 min 
Cooldown  5 min 
Teacher Reflection Questions
As you finish up this unit, reflect on the norms and activities that have supported each student in learning math. List ways you have seen each student grow as a young mathematician throughout this work. List ways you have seen yourself grow as a teacher. What will you continue to do and what will you improve on in the next unit?
Suggested Centers
 Number Puzzles: Multiplication and Division (4–5), Stage 2: Multidigit Factors (Addressing)
Print Formatted Materials
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Additional Resources
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