# Lesson 6

Expressions for Volume

### Lesson Purpose

The purpose of this lesson is for students to use their understanding of the structure of rectangular prisms to find volume and write numerical expressions to represent volume.

### Lesson Narrative

In a previous lesson students learned to find the volume of a rectangular prism by multiplying the number of cubes in a base layer by the number of layers. They connected this understanding to multiplication of length, width and height to find volume. They also used a two-dimensional representation of a base and its corresponding height to find the volume of a rectangular prism.

In this lesson students write and interpret numerical expressions that represent the volume of rectangular prisms. Students use what they know about rectangular prisms to reason whether or not an expression represents its volume.

During the next lesson, students will describe which standard cubic unit they would use to measure the volume of objects that are shaped like rectangular prisms. Consider which objects students see on a regular basis in their communities that are shaped like rectangular prisms and bring picture of those objects to show students during the next lesson. If possible, consider going on a prism scavenger hunt around the community before the next lesson.

Math Community

Tell students they will reflect on their identified norms at the end of this lesson.

• Engagement
• MLR8

### Learning Goals

Teacher Facing

• Find the volume of a right rectangular prism by multiplying the side lengths and connect that to finding volume by multiplying the area of the base by the height.
• Write and interpret numerical expressions in the context of the volume of a rectangular prism.

### Student Facing

• Let’s write expressions for the volume of rectangular prisms.

### Required Materials

Materials to Gather

Materials to Copy

• Matching Prisms and Expressions

### Required Preparation

Activity 1:

• Create a set of cards from the blackline master for each group of 2.
• Have connecting cubes available for students who need them.

Building Towards

### Lesson Timeline

 Warm-up 10 min Activity 1 15 min Activity 2 10 min Activity 3 10 min Lesson Synthesis 10 min Cool-down 5 min

### Teacher Reflection Questions

As students matched expressions to images of prisms today,  what evidence did you see that they are building on their understanding of the structure 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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