11+ Maths: Area and Perimeter of Compound Shapes on a Grid: Step-by-Step Example
23 October 2026
Understanding area and perimeter of compound shapes on a grid can feel tricky at first. By breaking the shape into smaller rectangles, you help your child see how each part fits together. This approach makes it easier for children to count squares and sides confidently.
Example question
Here is a compound shape on a grid. It looks like an L. The bottom part is 6 squares wide and 2 squares tall. The tall part is 2 squares wide and 5 squares tall.
Step 1: Split the shape into two rectangles.
Rectangle A: 6 squares wide, 2 squares tall.
Rectangle B: 2 squares wide, 3 squares tall (the top part above Rectangle A).
Step 2: Find the area of each rectangle.
Area of Rectangle A: 6 × 2 = 12 squares.
Area of Rectangle B: 2 × 3 = 6 squares.
Step 3: Add the areas to find the total area.
Total area = 12 + 6 = 18 squares.
Step 4: Find the perimeter. Count each outside edge square once.
Bottom edge: 6 squares.
Right edge up: 2 squares.
Right edge up (next section): 3 squares.
Top edge (short): 2 squares.
Left edge down: 5 squares.
Bottom edge in (short): 2 squares.
Add them: 6 + 2 + 3 + 2 + 5 + 2 = 20 squares.
The correct answers are: Area = 18 squares. Perimeter = 20 squares.
After working through this example, your child will spot how to split a compound shape and add up the areas and edges. Key insight: the same method works for any L-shaped or T-shaped figure on a grid. Now your child is ready to practise similar questions and build their skills.
