Shapes Made of Rectangles

Find the area of an L-shape by splitting it into rectangles.

Warm-up, learn, try it together, practice, then a quick check. About 15 minutes.

What children learn in Level 74

This shape isn't a rectangle, but it's made of two rectangles! A dashed line splits it.
The purple part is 3 × 4, which is 12. The green part is 2 × 2, which is 4. Add them: the area is 16 square units.
Split it the other way, and the area is still 16: 3 × 2 is 6, and 5 × 2 is 10.
With side lengths, use them to find each rectangle's sides. The whole bottom is 5, and the purple part is 3 of it, so the green part is 2 wide.

Georgia's K-12 Mathematics Standards:

3.GSR.7.2 — Determine the area of rectangles (or shapes composed of rectangles) presented in relevant problems by tiling and counting.