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Year 5 Maths | Learn, see, try

Area covers the inside; perimeter follows the edge

A garden bed needs soil to cover its surface and edging to go around its boundary. These are different measurements. Area tells us how much flat space is covered. Perimeter tells us the distance around the outside.

What to notice

Read what the question is asking before choosing a calculation. A rectangular shape has two lengths and two widths. Its inside can be covered by equal square units, but its boundary is measured in ordinary length units.

What to do

For a rectangle, multiply length by width to find area. To find perimeter, add all four sides. Draw labels on opposite sides if only two side lengths are given.

Why it works

A rectangle six centimetres long and four centimetres wide contains four rows of six one-centimetre squares. That is 24 square centimetres. Walking around it travels 6 + 4 + 6 + 4 centimetres, which is 20 centimetres.

Work through an example

Find the area and perimeter of this 6 cm by 4 cm rectangle.

6 cm4 cm
A rectangle is 6 cm long and 4 cm wide, divided into 24 unit squares.
  1. Count the grid: four rows of six squares give 24 squares. Each square covers 1 cm².
  2. Area = 6 × 4 = 24 cm².
  3. Perimeter = 6 + 4 + 6 + 4 = 20 cm. The units describe a distance, not a surface.

A common mistake

Adding 6 + 4 gives only two sides, not the entire perimeter. Writing 24 cm for the area also loses the meaning: area uses square units such as cm².

A strategy to try

Use the words “cover” and “border” as clues, then check the actual question. Shapes can have equal areas but different perimeters, so one measurement does not determine the other.

Try it now

Try three questions

No account is needed. These examples do not change saved learning progress. Choose an answer and check it for an explanation; you can try again.

1. What is the area of a rectangle 5 cm long and 3 cm wide?

2. What is the perimeter of a rectangle 5 cm long and 3 cm wide?

3. A rectangular mat is 8 m long and 2 m wide. What area does it cover?

For parents and carers

Make rectangles with square tiles and trace the edges. Compare a 6-by-4 rectangle with a 12-by-2 rectangle: each covers 24 squares, but their boundaries are different lengths. Let the model explain why the two measurements cannot be swapped.

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