How to explain tips in perimeter of squares & rectangles to your child
27 October 2026
Understanding how to calculate the perimeter of squares and rectangles is a key skill for 11+ maths. Children often find it easier to learn when they see a clear example with real numbers. Use this step-by-step question to show your child exactly what to do.
Example question
Find the perimeter of a rectangle with length 5 cm and width 3 cm.
Step 1: Write down the lengths of the sides. The rectangle has two sides of 5 cm and two sides of 3 cm.
Step 2: Add all the sides together: 5 cm + 3 cm + 5 cm + 3 cm = 16 cm.
Key insight: You can also use the formula, which is (length + width) × 2. So, (5 cm + 3 cm) × 2 = 8 cm × 2 = 16 cm.
The perimeter is 16 cm.
Now your child can spot the sides of a rectangle and knows how to find the perimeter using addition or the simple formula. They will be ready to practise more questions just like this, building confidence for the 11+ exam.
