Learn the idea
Volume measures the space a solid occupies. For a rectangular prism made of unit cubes, count cubes in one complete layer, then multiply by the number of layers.
- Multiply the number of rows by the cubes in each row.
- Multiply cubes per layer by the number of layers.
- Express the answer in cubic units.
LET’S WORK IT OUT
Worked example
A box has 4 cubes in each row, 3 rows per layer, and 2 layers. Find its volume.
4 × 3 × 2 = 24 cubic units
Each layer contains twelve cubes. Two complete layers contain twenty-four cubes.
A mistake to watch for
Counting only the visible top layer misses the cubes underneath.
YOUR TURN
Try three practice questions
Enter your answer, then check the explanation. You can also open each explanation to study it. These three questions check understanding; they are not a mastery score.
Question 1
A prism has dimensions 3, 2, and 4 units. Enter its volume in cubic units.
Answer and explanation
24 — Each layer has six cubes; four layers contain 24.
Question 2
A prism has dimensions 5, 2, and 3 units. Enter its volume in cubic units.
Answer and explanation
30 — Ten cubes per layer times three layers gives 30.
Question 3
A prism has dimensions 4, 4, and 2 units. Enter its volume in cubic units.
Answer and explanation
32 — Sixteen cubes per layer times two layers gives 32.
For parents and teachers
Build two layers with blocks, then describe how many cubes each layer contains.
Ask your learner to explain the method before moving on. This lesson covers one focused skill and is not a complete curriculum assessment.