Practice Set · Part 1
Determine the Volume of Rectangular Prisms
Pick up where we left off
Where we left off
Our goal: I can find the volume of a rectangular prism with whole-number edges using length × width × height, explain why the method works, and use it on a problem I have not seen before.
The big idea: To find the volume of a box, multiply all three edges: V = length × width × height — and you can say why it is true, and where it would stop being true.
Model to copy — Watch me
- My time capsule box is 6 long, 4 wide, and 3 tall. I write the formula: V = length × width × height.
- I put in the numbers: V = 6 × 4 × 3.
- First I multiply two of them: 6 × 4 = 24.
- Then I multiply by the last one: 24 × 3 = 72.
- So the volume is 72 cubic units. I use cubic units because volume fills space in 3 directions.
Start here
You did these with your group. Now do them on your own — the model above is yours to copy.
- 1
Same stepsFinish what the group started. Use the model above, step for step.
Try it together — then prove it: Now a smaller box: 5 long, 2 wide, 2 tall. What formula do we use? Let's put in the numbers: V = 5 × 2 × 2. What is 5 × 2? We got 10. Now multiply 10 × 2. What is the volume? Yes, V = 20 cubic units. Don't forget the cubic units! Now prove it: say why that move had to work at all — not just that it did.Show your work - 2
Warm restartTo find the area of a composite figure, you first…
- Abreak it into basic shapes you know
- Bmeasure around the outside
- Cmultiply all the side lengths
- Dfind the longest side
How do you know?
- 3
Warm restartA figure is a 6 by 4 rectangle with a 2 by 3 rectangle attached. What is the total area?
- A30 square units
- B24 square units
- C15 square units
- D144 square units
How do you know?
- 4
Warm restartA 10 by 8 rectangular garden has a 3 by 3 square patio cut out of it. What area is left?
- A71 square units
- B89 square units
- C80 square units
- D62 square units
How do you know?
Practice Set · Part 2
Determine the Volume of Rectangular Prisms
Keep going
You answered these out loud. Now write them.
Answer, then say how you know — the reason is the part that counts.
- 5
Think it throughWhat is the volume of the large box?
- A7,776 in³
- B4,752 in³
- C3,024 in³
- D60 in³
Why is that the answer?
- 6
Think it throughWhat is the volume of the medium box?
- A2,520 in³
- B3,024 in³
- C3,240 in³
- D4,752 in³
How do you know? Give a second reason as well.
- 7
Think it throughHow many more cubic inches does the large box hold?
- A4,752 in³
- B10,800 in³
- C1,728 in³
- D3,024 in³
Explain your thinking. What would have to change for a different choice to be right?
- 8
Back to the modelContainer C holds the most (96 in³) and Container B holds the least (50 in³). What do you notice about the dimensions that make one volume larger than another?
Practice Set · Part 3
Determine the Volume of Rectangular Prisms
Words and reasoning
Word bank · Banco de palabras
Use the words
Fill each blank with a word from the bank.
- The number of unit cubes inside a prism, found with V = l × w × h, is the ___.
- The amount of space inside a three-dimensional solid is its ___.
- A solid with six rectangular faces, like a box, is a ___.
- The unit used to measure volume, like cubic centimeters, is ___.
Explain the thinking
- 9
Find the mistakeAnother student made this exact mistake in this lesson. Explain why it is wrong, then write what they should have done.
The mistake: A common mistake in Volume with Whole Number Edges is multiplying only two of the three edges and stopping there — for example, seeing a box that is 6 in long, 4 in wide, and 3 in tall, multiplying just 6 × 4 = 24, and calling that the volume, when 24 is only the area of the bottom face (in square inches), not the volume of the whole box. - 10
Say moreContainer C is 8 × 3 × 4 and Container B is 5 × 5 × 2. How did you count or multiply the unit cubes to find each volume, and which holds more?
- 11
Write your ownWrite your own problem about this situation, then solve it and show the answer. The situation: Two time capsule containers sit side by side. Capsule A is 4 in long, 3 in wide, and 8 in tall. Capsule B is 6 in long, 6 in wide, and 6 in tall. A classmate says Capsule A must hold more because it looks taller.
Show your work
Practice Set · Part 4
Determine the Volume of Rectangular Prisms
Show what you know
Last check
These two come from Lesson 5.4. If they are shaky, that is the lesson to revisit — not this one.
- 12
Show what you knowExplain your thinking — A rectangular prism has l = 11 in, w = 5 in, h = 4 in. What is the volume?
- A220 in³
- B55 in³
- C220 in²
- D200 in³
Explain your choice.
- 13
From Lesson 5.4Explain your thinking — A composite figure is made of a 9 ft x 7 ft rectangle and a 3 ft x 4 ft rectangle joined together. What is the total area?
- A75 sq ft
- B63 sq ft
- C12 sq ft
- D75 ft
How do you know?
- 14
From Lesson 5.4What will the carpet cost?
- A$580
- B$116
- C$300
- D$1,160
How do you know?
Be honest — this tells your teacher what to do next
| I can… | Not yet | Getting there | Got it |
|---|---|---|---|
| I can find the volume of a rectangular prism with whole-number edges using length × width × height, explain why the method works, and use it on a problem I have not seen before. | |||
| I can explain why it works: To find the volume of a box, multiply all three edges: V = length × width × height… | |||
| I can justify my answer to a skeptic and connect it to a second strategy or representation. |
One question I want to ask my group next time