5th Grade Math · Volume of Rectangular Prisms
Find a missing edge Worksheets
Fresh practice, ready to print. Answer key included.
The volume and two edges are given. Find the third.
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How it works: a quick refresher
The rules this worksheet practices, then one problem worked from start to finish.
| Strategy | How it works |
|---|---|
| Volume is the space inside | Volume counts unit cubes and is measured in cubic units, such as cm³. |
| Layers | Count the cubes in the bottom layer (length × width), then multiply by the number of layers (height). |
| The formula | V = l × w × h. A 5 cm by 3 cm by 4 cm prism holds 5 × 3 × 4 = 60 cm³. |
| Any order | You can multiply the three edges in any order and get the same volume. |
| Missing edge | Divide the volume by the two edges you know: 60 ÷ (5 × 3) = 4 cm. |
Worked example
A prism is 6 cm long, 4 cm wide and 3 cm high. Find its volume.
- 1The bottom layer is 6 × 4 = 24 unit cubes.
- 2There are 3 layers, so multiply: 24 × 3 = 72.
- 3The volume is 72 cm³.
Ready-made versions
Three fixed versions you can link to or share. Each is a PDF with its own answer key.
- Find a missing edge Worksheets, version 1Worksheet PDFAnswer key PDF
- Find a missing edge Worksheets, version 2Worksheet PDFAnswer key PDF
- Find a missing edge Worksheets, version 3Worksheet PDFAnswer key PDF
Grade level and standard
Written for 5th grade math (measurement) and aligned to CCSS 5.MD.C.5. It also works as review in later grades.
Common questions
- Is there an answer key?
- Yes. Every worksheet has a matching answer key with each answer worked on the same grid or layout as the question. The worksheet code printed at the bottom of each page pairs a sheet with its key.
- How do we count the cubes we cannot see?
- Count the cubes in one layer from the top face, then multiply by how many layers tall the prism is. Every layer is the same, so the hidden cubes are counted too.
- Why is the answer in cubic units?
- Volume fills space in three directions, so it is counted in cubes. A length is in cm, an area is in square cm, and a volume is in cubic cm, written cm³.
- How many different versions are there?
- About a million per skill. Each time you press the button the problems are generated fresh, so you can print a different version for every student, a retake, or another night of practice.
- Are the worksheets free?
- Yes. They are free to print and copy for your home or classroom, with no sign-up.
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