11+ Maths Perimeter Practice: A Parent's Guide
21 October 2026
Understanding perimeter
Perimeter is the total distance around the edge of a shape. In 11+ maths, children are often asked to find the perimeter of rectangles, compound shapes or regular polygons.
It is important because perimeter questions test careful reading, attention to units and methodical working.
Why perimeter matters in 11+ exams
Perimeter questions appear regularly in 11+ papers. Children need to recognise what the question is asking for and make sure they use the correct units.
Mistakes often happen when a child mixes up perimeter with area, or forgets to add all the sides.
Worked example: perimeter of a rectangle
Find the perimeter of a rectangle with sides 5 cm and 4 cm.
Step 1: Write down the lengths of all four sides. A rectangle has two sides of 5 cm and two sides of 4 cm.
Step 2: Add the lengths together. 5 cm + 4 cm + 5 cm + 4 cm
Step 3: Calculate the total. 5 + 4 + 5 + 4 = 18
The correct answer is 18 cm.
Key insight: Check the question and the units
Always check whether the question asks for perimeter, area or volume. Remind your child to add all the sides, and double-check that the answer is in the correct unit, such as cm or m. If the shape has missing sides, look for clues or use other sides to work them out.
