Area of decomposed rectangles (two-part rectangles; grade 3 math)

For example, let's say the larger rectangle is 4 by 7 units, and it's divided into parts that are 4 by 2 and 4 by 5 units. Then:

4 × 7 = 4 × 2 + 4 × 5 and also:

4 × (2 + 5) = 4 × 2 + 4 × 5

We practice this concept with several exercises in the video.

See also

Perimeter — video lesson

Area and Perimeter Builder (online activity)

Math Mammoth Early Geometry — a self-teaching worktext for geometry topics in grades 1-3

Math Mammoth Grade 3 complete curriculum

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