Learn on PengiIllustrative Mathematics, Grade 5Chapter 1: Finding Volume

Lesson 5: Composite Figures: Volume of Combined Prisms

In this Grade 5 lesson from Illustrative Mathematics Chapter 1, students learn to find the volume of composite figures made up of two non-overlapping right rectangular prisms by decomposing the shape and adding the volumes of each part. Students practice applying the additive property of volume (5.MD.C.5.c), discovering that the same figure can be split into prisms in different ways yet yield the same total volume. Hands-on work with connecting cubes helps reinforce why the volume of a combined figure equals the sum of its component prisms.

Section 1

Decomposing Composite Figures

Property

The volume of a composite figure can be found by decomposing it into non-overlapping rectangular prisms and adding their individual volumes.

Vcomposite=Vprism 1+Vprism 2V_{\text{composite}} = V_{\text{prism 1}} + V_{\text{prism 2}}

Examples

  • An L-shaped figure can be decomposed into two rectangular prisms. The total volume is the sum of the volumes of the two smaller prisms.
  • A T-shaped figure can be split into a horizontal prism and a vertical prism. Its total volume is found by adding the volumes of these two parts.
  • A figure shaped like steps can be split into multiple rectangular prisms stacked on top of each other. The total volume is the sum of the volumes of all the steps.

Explanation

A composite figure is a three-dimensional shape made by combining two or more simpler shapes. To find the volume of a composite figure, we first break it down, or decompose it, into familiar shapes like rectangular prisms. After identifying the individual prisms, the next step is to find the volume of each one separately. The total volume of the composite figure is simply the sum of the volumes of all the individual prisms.

Section 2

Volume of Composite Prisms

Property

To find the volume of a composite solid made of rectangular prisms, calculate the volume of each individual prism and then add their volumes together.

Vtotal=Vprism 1+Vprism 2V_{\text{total}} = V_{\text{prism 1}} + V_{\text{prism 2}}

Examples

Book overview

Jump across lessons in the current chapter without opening the full course modal.

Continue this chapter

Chapter 1: Finding Volume

  1. Lesson 1

    Lesson 1: Introduction to Volume and Measurement

  2. Lesson 2

    Lesson 2: Calculate Volume Using Layers

  3. Lesson 3

    Lesson 3: Side Lengths and Volume Expressions

  4. Lesson 4

    Lesson 4: Cubic Units of Measure

  5. Lesson 5Current

    Lesson 5: Composite Figures: Volume of Combined Prisms

  6. Lesson 6

    Lesson 6: Apply Volume Knowledge

Lesson overview

Expand to review the lesson summary and core properties.

Expand

Section 1

Decomposing Composite Figures

Property

The volume of a composite figure can be found by decomposing it into non-overlapping rectangular prisms and adding their individual volumes.

Vcomposite=Vprism 1+Vprism 2V_{\text{composite}} = V_{\text{prism 1}} + V_{\text{prism 2}}

Examples

  • An L-shaped figure can be decomposed into two rectangular prisms. The total volume is the sum of the volumes of the two smaller prisms.
  • A T-shaped figure can be split into a horizontal prism and a vertical prism. Its total volume is found by adding the volumes of these two parts.
  • A figure shaped like steps can be split into multiple rectangular prisms stacked on top of each other. The total volume is the sum of the volumes of all the steps.

Explanation

A composite figure is a three-dimensional shape made by combining two or more simpler shapes. To find the volume of a composite figure, we first break it down, or decompose it, into familiar shapes like rectangular prisms. After identifying the individual prisms, the next step is to find the volume of each one separately. The total volume of the composite figure is simply the sum of the volumes of all the individual prisms.

Section 2

Volume of Composite Prisms

Property

To find the volume of a composite solid made of rectangular prisms, calculate the volume of each individual prism and then add their volumes together.

Vtotal=Vprism 1+Vprism 2V_{\text{total}} = V_{\text{prism 1}} + V_{\text{prism 2}}

Examples

Book overview

Jump across lessons in the current chapter without opening the full course modal.

Continue this chapter

Chapter 1: Finding Volume

  1. Lesson 1

    Lesson 1: Introduction to Volume and Measurement

  2. Lesson 2

    Lesson 2: Calculate Volume Using Layers

  3. Lesson 3

    Lesson 3: Side Lengths and Volume Expressions

  4. Lesson 4

    Lesson 4: Cubic Units of Measure

  5. Lesson 5Current

    Lesson 5: Composite Figures: Volume of Combined Prisms

  6. Lesson 6

    Lesson 6: Apply Volume Knowledge