Perimeter calculation practice for 11 plus: GL & CEM style
19 October 2026
Why perimeter matters for 11 plus
Understanding how to calculate perimeter is a key skill for the 11 plus maths exam. Both GL and CEM papers often include questions on perimeter, so regular practice helps children feel prepared and confident.
What is perimeter
The perimeter is the total distance around the outside of a shape. To find the perimeter, you add up the lengths of all the sides.
Worked example
Let's take a rectangle with sides of 5 cm and 4 cm.
First, write down the lengths of all the sides: 5 cm, 4 cm, 5 cm, and 4 cm.
Add the sides together: 5 + 4 + 5 + 4.
Work out the total: 5 + 4 = 9, then 9 + 5 = 14, and 14 + 4 = 18.
The perimeter of the rectangle is 18 cm.
Step-by-step approach
Start by identifying each side of the shape and writing down its length.
Check if any sides are equal, as in rectangles or squares, to help with adding.
Add each side one at a time, making sure not to miss any.
Double-check your total to avoid simple mistakes.
Key insight: Regular practice with different shapes, including rectangles, squares and compound shapes, helps children build confidence and accuracy when calculating perimeter for the 11 plus.
