Surface area with a net: 5th grade math lesson

What this lesson shows

A box 4 by 3 by 2 unfolds into 6 rectangles: two 4 by 3, two 4 by 2, and two 3 by 2. 12 + 12 + 8 + 8 + 6 + 6 is 52 square units.

The worked example

The lesson works this one step by step: A box 4 by 3 by 2 cm. Then your kid tries one like it on paper.

The steps

Unfold the box into a net
Top and bottom match
Front and back match
The 2 ends match
Add all 6 faces: square units

Helping at home

Measure the box, then unfold it into a net of 6 rectangles: the top and bottom, the front and back, and 2 ends. Find each face’s area, then add all 6. Surface area covers the outside, in square units; volume fills the inside, in cubic units.

If your kid gets stuck

Draw the net. Which faces match?

Watch it with Lux

With Lux, this lesson is a narrated video and a printed page your kid works on. Then Lux helps with the same math on their own worksheet, one question at a time.

See how Lux works

Surface area with a net