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4th grade math · Unit 8: Angles, perimeter, and area

Same area, different perimeters

What this lesson shows

12 tiles in different rectangles: same area, different perimeters.

The worked example

The lesson works this one step by step: 12. Then your kid tries one like it on paper.

The steps

  1. Same tiles, same area
  2. Try every rectangle
  3. Add the four sides
  4. Closest to a square: least

Helping at home

Find every way to make the number by multiplying two whole numbers: each pair is a rectangle of tiles. The area is always the number of tiles. Add the four sides for each perimeter, and compare: the long, thin one has the most edge, and the one closest to a square has the least.

If your kid gets stuck

Start with one long row, then try 2 rows, 3 rows, and so on.

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

Standards

  • Common Core 4.MD.A.3
    Apply the area and perimeter formulas for rectangles in real world and mathematical problems. For example, find the width of a rectangular room given the area of the flooring and the length, by viewing the area formula as a multiplication equation with an unknown factor.
Matches standards in 48 statesSee each state's code

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