11+ Area and Perimeter
Children must keep area (space inside) and perimeter (distance around) separate, and handle compound shapes by splitting them up.
Perimeter is the total distance around the outside of a shape — add up every side. Area is the amount of surface inside; for a rectangle, area = length × width.
For compound (L-shaped) shapes, split them into rectangles, work out each area, then add. For perimeter, work all the way around the outside, using subtraction to find any missing side lengths.
Watch the units: perimeter is in length units (cm), area is in square units (cm²). Mixing them up is a frequent and avoidable error.
Worked examples
Q. A rectangle is 8 cm long and 5 cm wide. Find its area and perimeter.
Area = 8 × 5 = 40 cm². Perimeter = 8 + 5 + 8 + 5 = 26 cm.
Q. An L-shape is made of a 6×4 rectangle and a 2×3 rectangle. Find the total area.
First area = 6 × 4 = 24. Second area = 2 × 3 = 6. Total = 24 + 6 = 30 cm².
Common mistakes
- Writing area answers without the squared (cm²) unit.
- Adding only some sides when finding perimeter of compound shapes.
- Confusing which measurement the question wants.
FAQs
Is the area formula given in the 11+?+
Usually not — children are expected to know area = length × width for rectangles and to reason about compound shapes themselves.
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