Box nets: count every face

Grade 6 mathematics · 15 minutes · Surface area

Use a rectangular prism net to calculate surface area without confusing it with volume.

Classroom activity

A closed rectangular box is 4 cm long, 3 cm wide, and 2 cm high.

1. Sketch a net with all six faces and label their dimensions.
2. Find the area of each face. Group equal faces to avoid double counting or missing one.
3. Calculate the total area of paper needed to cover the box, ignoring overlap.
4. Compare this with the box volume. Explain why one uses square units and the other uses cubic units.

Ask a partner to check that your net includes every face.

Check understanding

A cube has side length 3 cm. Find its surface area and its volume. Label the units.

Teacher guide and answers

The face pairs have areas 12, 8, and 6 cm². Surface area is 2(12 + 8 + 6) = 52 cm². Volume is 24 cm³. The cube check is 54 cm² and 27 cm³. Surface area counts covering squares; volume counts filling cubes. Support with a physical box or six separate rectangles.

You may use, print, adapt, and share this example for teaching. Keep the ClassLattice attribution when redistributing the original.

Grade 6 topic reference. Confirm your adopted standards; topic guidance does not certify alignment.