11+ Perimeter, Area & Volume
This topic tests whether children can apply a small number of formulas carefully. Perimeter is the distance all the way around, area is the space inside (in square units), and volume is the space a solid takes up (in cubic units). Mixing up these three — and their units — is the single most common source of lost marks.
Harder 11+ questions use compound shapes made from rectangles. The trick is to split the shape into rectangles, work out each part, then add or subtract as needed.
What the 11+ tests in perimeter, area & volume
- check_circlePerimeter of rectangles and compound shapes
- check_circleArea of rectangles, and compound shapes made from rectangles
- check_circleVolume of cubes and cuboids
- check_circleChoosing the correct units (cm, cm², cm³)
- check_circleFinding a missing side when the area or perimeter is given
- check_circleReal-life problems (carpet, fencing, boxes)
Worked example
A rectangle is 8 cm long and 5 cm wide. Find its area and its perimeter.
- Area of a rectangle = length × width = 8 × 5.
- Give area in square units: 40 cm².
- Perimeter = 2 × (length + width) = 2 × (8 + 5).
- Perimeter = 2 × 13 = 26 cm.
checkAnswer: Area = 40 cm², Perimeter = 26 cm
Common mistakes to avoid
- errorUsing the wrong units — writing cm instead of cm² for area.
- errorAdding only two sides for perimeter instead of all four.
- errorConfusing area (×) with perimeter (+) under time pressure.
Top tips
- lightbulbSay the units out loud: area is 'square', volume is 'cube'.
- lightbulbFor compound shapes, draw the split into rectangles and label every side first.
- lightbulbTo find a missing side from the area, divide the area by the known side.
Practise perimeter, area & volume free
ElevenEdge gives your child adaptive perimeter, area & volume questions at just the right level, with a worked solution on every one. No card needed to start.
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