Lesson 8

Lesson Purpose

The purpose of this lesson is for students to recognize the structure of a solid figure made up of two non-overlapping 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.

Building On

Lesson Timeline

 Warm-up 10 min Activity 1 20 min Activity 2 15 min Lesson Synthesis 10 min Cool-down 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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