In Grade 5, students find the volume of a rectangular prism using a formula: V = length × width × height, or V = B × h, where B is the area of the base.
Volume is measured in cubic units, such as cubic inches or cubic centimeters, because it counts unit cubes.
Official benchmarkFind the volume of a right rectangular prism with whole-number side lengths using a visual model and a formula.
On the FAST test: part of the Grade 5 reporting category Geometric Reasoning, Measurement, and Data Analysis and Probability, which is about 23–29% of the test.
Worked Examples
Worked Example 1
Using V = l × w × h
A prism is 6 cm long, 4 cm wide, and 3 cm tall.
1V = 6 × 4 × 3.
26 × 4 = 24; 24 × 3 = 72.
Answer: 72 cubic centimeters
Worked Example 2
Using V = B × h
The base of a prism has an area of 20 sq in. The height is 5 in.
1V = B × h.
220 × 5 = 100.
Answer: 100 cubic inches
Common Mistakes to Watch For
Adding the dimensions
Wrong:6 + 4 + 3 = 13 cubic cm
Volume multiplies the three dimensions: 6 × 4 × 3 = 72 cubic cm.
Using square units
Wrong:Volume = 72 square cm
Volume counts cubes, so the unit is cubic: 72 cubic centimeters.
Helpful Math Tip
Multiply the two easiest numbers first. The order of multiplication does not change the volume.
Independent Educational Platform. FastChomp is published by Tropical Learning LLC and is not affiliated with, sponsored by, or endorsed by the Florida Department of Education. FAST and Star assessment names are referenced for informational purposes only. FastChomp practice questions are original educational materials, not official Florida FAST assessment questions.
