Grade 5 · lesson 2 of 4

Calculate Volume from Full Unit-Cube Layers

Use the supplied whole-number prism dimensions to draw one layer.

About 20 minutes, plus any extended practice

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Supplied materials

  • Paper and a pencil; drawing and spoken explanations are welcome. An adult may read directions and options aloud.
  • Supplied worked-case record: A prism is 6 units by 3 units by 4 units.
  • All quantities and shape descriptions are supplied in the worked example and questions; no purchase or personal information is needed.

Learn the idea

Volume counts equal cubes filling a solid without gaps or overlap. A rectangular layer contains length times width unit cubes. Multiplying the layer count by the number of layers gives the volume. The three length dimensions create cubic units, which differ from area’s square units.

Use the supplied whole-number prism dimensions to draw one layer. Find its cube count, then multiply by the number of full layers. Check the result with the three-factor product length × width × height.

Count complete layers, including stated hidden layers. Area uses two dimensions; prism volume uses three. Draw one rectangular cube layer and record how many identical layers fill the solid.

  1. Draw one rectangular cube layer and record how many identical layers fill the solid.
  2. Follow the worked example. Point to each number or shape feature and say what it tells you.
  3. Use the supplied whole-number prism dimensions to draw one layer.
  4. Try the question and then the three practice questions. Check your answers and explain any change you make.
Worked example

See the method in action

A prism is 6 units by 3 units by 4 units. Each layer has eighteen unit cubes and four layers contain 72. Thus volume is 6×3×4=72 cubic units. The layer’s eighteen square-unit base area is not the full solid’s volume by itself. Count complete layers, including stated hidden layers. Area uses two dimensions; prism volume uses three. Draw one rectangular cube layer and record how many identical layers fill the solid.

Your turn

Check your reasoning

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Helpful tips
  • Count complete layers, including stated hidden layers.
  • Area uses two dimensions; prism volume uses three.
A right rectangular prism is 3 units by 4 units by 2 units. What is its volume in cubic units?

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See the answer and explanation

24

Multiply cubes per layer by the full layer count. The result is 24.

Take it further

A 7×5×3 prism holds 105 cubic units.

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More practice: try new cases

Choose an answer for each problem. Explain your method on paper, then use the feedback to decide what to revisit.

More practice: try new cases
1. A right rectangular prism is 4 units by 4 units by 2 units. What is its volume in cubic units?
Need a hint?
  • Count complete layers, including stated hidden layers.
  • Area uses two dimensions; prism volume uses three.
2. A right rectangular prism is 5 units by 4 units by 2 units. What is its volume in cubic units?
Need a hint?
  • Count complete layers, including stated hidden layers.
  • Area uses two dimensions; prism volume uses three.
3. A right rectangular prism is 6 units by 4 units by 2 units. What is its volume in cubic units?
Need a hint?
  • Count complete layers, including stated hidden layers.
  • Area uses two dimensions; prism volume uses three.

Your choices are temporary. Feedback appears after you check all the answers.

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These LifeStarter passages, scenarios and exercises are authored for this Academy with AI assistance and review. External resources keep their publishers’ terms. A grade label suggests a starting level; it does not establish alignment with your school’s complete requirements.