Lesson 5.105.10 Small Group · Group 1
Start hereWords, worked example, and sentence starters
Learning target With my small group, I can find the volume of a rectangular prism, including ones with fractional edge lengths, using base area × height — one step at a time, with support.
Start hereWords for this lesson
Read each word before you begin. Say it out loud.
| Word | What it means | Example |
|---|---|---|
| VolumeSpanish: Volumen | How much space is inside a solid shape. | A box 2 × 1.5 × 1 = 3 ft³ — it holds 3 cubic feet of stuff |
| Rectangular prismSpanish: Prisma rectangular | A solid box shape with six flat rectangle sides. | A tissue box, a fish tank, a brick — all rectangular prisms |
| Cubic unitsSpanish: Unidades cúbicas | The units used to measure space inside, like cubic inches. | 1 ft³ = a cube that is 1 foot on every edge |
| DimensionsSpanish: Dimensiones | How long, how wide, and how tall a shape is. | A box with dimensions 4 × 3 × 2 means l = 4, w = 3, h = 2 |
| Base areaSpanish: Área de la base | The area of the bottom of a solid. Volume = base area × height. | If the base is 6 × 4 = 24 cm² and h = 3, then V = 24 × 3 = 72 cm³ |
How it worksWorked example
These numbers are not on your problems. The steps are. Follow them with your own numbers.
A time capsule is 2 ft long, 1.5 ft wide, and 1 ft tall. Find its volume.
- Write the volume formula: V = l × w × h
- Multiply the length by the width: 2 × 1.5 = 3
- Multiply by the height: 3 × 1 = 3
- The volume is 3 cubic feet.
Now you trySame steps, your turn
The steps are the same as the worked example. The numbers are yours. Do the work.
A box is 4 units long, 2 units wide, and 0.5 units tall. Use the base area to find its volume.
Say it and write itSentence starters
Finish each sentence out loud with a partner. Then use them in your writing.
- Capsules A and B both have V = because × × = × × . I'd choose because .
Word bank VolumeRectangular prismCubic unitsDimensionsBase area3volumesamedifferentdimensionsshapelength
Watch outA common mistake
A common mistake in Volume of Rectangular Prisms is rounding a fractional edge length to the nearest whole number before multiplying, instead of using the exact fraction or decimal. For a box that is 2 ft × 1.5 ft × 1 ft, a student might round 1.5 down to 1 and compute 2 × 1 × 1 = 2 ft³, but the correct volume uses the exact edge length: 2 × 1.5 × 1 = 3 ft³ — a full cubic foot larger. Before you submit, ask: 'Did I multiply using the exact fractional or decimal edge length, or did I round it off first?'
Lesson 5.105.10 Small Group · Group 1
Group 1Supported practice
Learning target With my small group, I can find the volume of a rectangular prism, including ones with fractional edge lengths, using base area × height — one step at a time, with support.
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1Complete each step, then write the final answer.
The height is a decimal: 1.5 in. A box is 6 in long, 2 in wide, and 1.5 in tall. Use the base area to find its volume.
- 1What is the base area, 6 × 2?
- 2The height is 1.5. How many layers of 12 cubes fit?
- 3What is 12 × 1.5, the volume?
Final answer: -
2Complete each step, then write the final answer.
A box is 5 ft long, 3 ft wide, and 1/2 ft tall. Find its volume.
- 1What is the base area?
- 2Multiply by 1/2. What is the volume?
- 3Check the other way. What is 5 × 3 × 1/2?
Final answer: -
3Complete each step, then write the final answer.
A box is 2 cm long, 2 cm wide, and 0.5 cm tall. Find its volume.
Show your workHint Find the base area first. Multiplying by 0.5 is the same as taking half.
Final answer: -
4Complete each step, then write the final answer.
A time capsule is 3 ft long, 1.5 ft wide, and 2 ft tall. Find its volume.
Show your workHint The base is 3 ft by 1.5 ft. Find its area, then multiply by the height.
Final answer: -
5Complete each step, then write the final answer.
A fish tank is 20 in long, 10 in wide, and 12.5 in tall. How many cubic inches of water can it hold?
Show your workHint The water fills the space inside, so find the volume: base area × height.
Final answer: -
6Complete each step, then write the final answer.
Ava finds the volume of a box that is 4 m by 2.5 m by 2 m. She writes 4 + 2.5 + 2 = 8.5. What is the volume?
Show your workHint Volume multiplies. Find the base area, then multiply by the height.
Final answer:
Explain your thinkingDoes a decimal or fraction edge change the steps for volume? Use base area and layers to explain.
Sentence starter The steps stay the same because ___. · A height of {1/2} means ___ of a layer.