Calculate the area of shapes made from 2 or more rectangles | Maths

Starter quiz

Match the multiplication equation to the correct answer.

25 x 8

⇔

= 200 ✓

20 x 12

⇔

= 240 ✓

2 x 125

⇔

= 250 ✓

30 x 7

⇔

= 210 ✓
Which of these compound shapes has the largest area?

a

b ✓
Which would be the most efficient strategy to calculate the area of this compound rectilinear shape?

Split it into two rectangles using a vertical line. Combine the two areas.

Draw a rectangle around the shape. Subtract the area of the gap rectangle. ✓

Split it into two rectangles using a horizontal line. Combine the two areas.
What are the missing dimensions for the square?

12 cm and 12 cm

11 cm and 12 cm

11 cm and 10 cm

11 cm and 11 cm ✓
Tick all the possible pairs of dimensions from the list.

3 cm and 10 cm

32 cm and 1 cm ✓

16 cm and 2 cm ✓

8 cm and 4 cm ✓

4 cm and 6cm
The area of this compound shape is 227 cm². What is the missing dimension?

5 cm²

7 cm² ✓

8 cm²

6 cm²

Exit quiz

A ______ shape is one that is made up of two or more shapes.

rectangle

rectilinear

square

compound ✓
This is an image of the French flag. It consists of three rectangles of equal size. Calculate the area of the blue part. ______ cm²

'63 ' ✓
This image is of the flag from the Netherlands. It consists of three rectangles of equal size. Calculate the total area of the flag. ______ cm²

'99' ✓
This rectilinear shape is made up of four identical rectangles. Choose an efficient method to calculate the area. A = ______ cm²

'96' ✓
Laura has chosen to decompose this compound rectilinear shape into two rectangles. Which multiplications will she use to help calculate the area?

9 cm × 6 cm ✓

11 cm × 9 cm

11 cm × 3 cm

3 cm × 5 cm ✓
To calculate an area of the playground, Lucas has chosen to calculate the whole area and then subtract the missing part. Correctly order the calculations that he would do.

1

⇔

12 m × 11 m = 132 m²

2

⇔

3 m × 3 m = 9 m²

3

⇔

132 m² - 9 m² = 123 m²

Worksheet

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Lesson Details

Key learning points

To find the area of a rectangle you multiply the length by the width.
Compare different methods to decompose shapes and decide which is the most efficient.
Choose the most efficient calculation strategies to calculate the area of a compound rectilinear shape.

Common misconception

There is only one way to split a compound shape to calculate the area.

Make time in the lesson to model and discuss different ways of calculating the area of compound shapes. Include strategies that move parts of the shape to simplify the shape and the calculations needed.

Keywords

Compound - A compound shape is made up of two or more shapes.