Surface Area of Boxes & Cubes

3 pairs of identical opposite faces: S = (l×w + l×h + w×h) × 2

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About This Practice

A box has 6 rectangular faces, and opposite faces are identical: top & bottom are both length × width, front & back are both length × height, left & right are both width × height. Unfold the box into a flat net, color the three opposite pairs, and the surface-area formula explains itself: S = (l×w + l×h + w×h) × 2. Deal new edges and try again!

Cut a box along its edges and its 6 rectangular faces unfold into a net one by one; top-bottom, front-back and left-right pairs light up in matching colors. Tap Next and watch the surface-area formula (l×w + l×h + w×h) × 2 build up step by step.

MediumEstimated Time: 15minsurface areanetsrectangular prismcube

How to Play

  1. Watch the net: the 6 rectangles unfold one by one.
  2. Tap “Next”: the three opposite pairs light up in turn — each pair is identical.
  3. Tap again: the formula shows three area terms, color-matched to the three pairs.
  4. One more tap: add the terms, multiply by 2 — the surface area appears.
  5. Tap “New Box” and unfold a fresh set of edges.

Learning Objectives

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