# Lesson 9

### Lesson Purpose

The purpose of this lesson is for students to find the volume of figures composed of two non-overlapping right rectangular prisms by adding the volumes of the non-overlapping parts.

### Lesson Narrative

In the previous lesson, the figures students worked with showed the unit cubes, providing the opportunity to visualize the number of unit cubes and find volume in a variety of ways. In this lesson, the figures composed of two non-overlapping right rectangular prisms do not show the individual cubes. This encourages students to apply the volume formulas and make connections between expressions and the way the figures can be decomposed. Given an expression and a solid figure composed of two rectangular prisms, students determine how to decompose the figure to match the given expression (MP2, MP7).
• Representation
• MLR7

### Learning Goals

Teacher Facing

• Find the volume of a figure composed of rectangular prisms in which unit cubes are not shown.

### Student Facing

• Let’s find the volume of more figures.

### Required Materials

Materials to Copy

• Isometric Dot Paper Standard

Building Towards

### 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 connections did students make between the different strategies shared? What questions did you ask to help make the connections more visible?

### Suggested Centers

• Five in a Row: Multiplication (3–5), Stage 4: Three Factors (Addressing)
• Rolling for Fractions (3–5), Stage 1: Equivalent Fractions (Supporting)

### Print Formatted Materials

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