Lesson 8
Figures Made of Prisms
Lesson Purpose
The purpose of this lesson is for students to recognize the structure of a solid figure made up of two nonoverlapping right rectangular prisms and understand that its volume is the sum of the volumes of the two rectangular prisms.
Lesson Narrative
In previous lessons, students found the volume of right rectangular prisms represented in images where the cubes were shown or not shown. In this lesson, they build separate rectangular prisms and put them together to emphasize the relationship between the volume of the individual smaller prisms and the volume of the whole figure. Then they find volumes of figures made from two rectangular prisms without first building each part. Students recognize that when the figure composed of two rectangular prisms is given, there are different ways to decompose the figure, leading to different calculations of the same volume.
 Engagement
 MLR7
Learning Goals
Teacher Facing
 Explain that the volume of a figure composed of rectangular prisms is the sum of the volumes of the prisms.
 Find the volume of a figure composed of rectangular prisms in which unit cubes are visible.
Student Facing
 Let’s find the volume of figures made of prisms.
Required Materials
Materials to Gather
Required Preparation
Activity 1:
 Each group of 2 needs at least 30 connecting cubes.
CCSS Standards
Lesson Timeline
Warmup  10 min 
Activity 1  20 min 
Activity 2  15 min 
Lesson Synthesis  10 min 
Cooldown  5 min 
Teacher Reflection Questions
What language did students use to demonstrate their understanding that the figures they worked with today were composed of rectangular prisms?
Suggested Centers
 Five in a Row: Multiplication (3–5), Stage 4: Three Factors (Addressing)
 Capture Squares (1–3), Stage 7: Multiply with 6–9 (Supporting)
Print Formatted Materials
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Additional Resources
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