Rectangle & Square Perimeter

Rectangle: (length + width) × 2; Square: side × 4

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About This Practice

Rectangle perimeter = (length + width) × 2, and square perimeter = side × 4. Use the + and − buttons to change the dimensions and watch the perimeter respond: +1 in length adds 2 to the perimeter, +1 on the side adds 4. The formulas are not memorized — they grow out of the shape before your eyes.

Use + and − to change a rectangle's length and width (or a square's side) and watch the perimeter respond: +1 in length adds 2 to the perimeter, +1 on the side adds 4. The formula updates live with the shape.

EasyEstimated Time: 10minrectangle perimetersquare perimeterformulasides

How to Play

  1. Add 1 to the rectangle’s length with the + button and see how much the perimeter grows.
  2. Then add 1 to the width and watch again.
  3. Think: why does +1 in length add 2 to the perimeter? (There are two lengths!)
  4. Switch to the square: +1 on the side makes the perimeter jump by 4.
  5. Read the formula beside the shape and match each number to its edges.

Learning Objectives

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