Calculate the area of a rectangle or decomposable rectilinear shape.
Free to use and free to share. There is no sign-up, no score, and nothing a child does here is recorded or sent anywhere.
Practise it now
This L-shape is awkward. Cut it into two rectangles you CAN measure.
Loading the interactive exercise. Nothing you do here is saved or scored.
A worked example
One question of the kind this skill is tested with, worked all the way through: the reasoning, and what the wrong answers are there to catch.
Counting the squares inside a shape
Esme covers this shape with 1 cm squares. What is the area?
Every side of this rectangle is marked in centimetres.
84 cm²
96 cm²
19 cm²
38 cm²
Answer: 84 cm²
How you get there
This rectangle is 12 cm by 7 cm, and 12 rows of 7 squares is 84 squares, so the area is 84 cm². The 38 cm right round the edge is the perimeter, which is a different measurement.
Why the other answers tempt
The distance round the edge is the perimeter; the area counts the squares that fit inside.
If they are stuck, say this
Cut the shape into rectangles you can measure, work out how many centimetre squares each one holds, then add those together.
This L-shape is awkward. Cut it into two rectangles you CAN measure.
A compound shape has no area formula of its own, so you make one: slice it into rectangles, find each area with width × height, and add. Perimeter is a different animal - it is the distance an ant walks all the way round the outside, so the cut you drew does not count. That is why area and perimeter almost never match.
Step 1. Slice it. Cut the shape into two rectangles, then add their areas.
Step 2. The ant walk. Walk the ant right round the edge. How far did it travel?
What to say if they get stuck
Drag along one of the faint grid lines inside the shape to make your cut.
A good cut leaves two neat rectangles - no L-shaped leftovers.
Area adds up when you cut. Perimeter does not: cutting makes new edges that were never on the outside.
The 11+ does not test these skills in isolation, and practising one in the wrong order wastes the practice. These are the skills the curriculum map connects this one to.
Both use labelled dimensions but measure different attributes.
How calculate area differs from the skills beside it
The same exercise practises one other skill, and telling them apart is often the difficulty rather than the exercise itself. On this page the skill is: calculate the area of a rectangle or decomposable rectilinear shape, and it stops where excludes volume.
Answered from what the skill map records about this skill, not from a template. Every answer here is on the page, and the same questions are the page's FAQ structured data.
Calculate the area of a rectangle or decomposable rectilinear shape. It is one of 55 named maths skills in the 11+, in the measure strand, and this page carries 1 interactive exercise that practises it.
The distance round the edge is the perimeter; the area counts the squares that fit inside. The wrong answers on this skill are built out of that, not out of random numbers, so it is worth naming out loud before your child meets it under time pressure.
No. To calculate area is to calculate the area of a rectangle or decomposable rectilinear shape. To calculate perimeter is to calculate the boundary length of a labelled rectilinear or polygonal shape. Learners may apply an area operation to a boundary-length task. Telling the two apart is often the real difficulty in the question.
Point at the next move rather than explaining the whole rule. Cut the shape into rectangles you can measure, work out how many centimetre squares each one holds, then add those together.
The skill map draws the line here: Excludes volume. A question past that line is testing a different named maths skill, which is worth knowing before you spend a week practising the wrong one.
The skill map connects it to calculate perimeter. Both use labelled dimensions but measure different attributes. That skill has its own page here.
Use Area Unfolder, embedded on this page. It is the exercise the skill map attaches to calculate area, it runs in the browser with no account to make, nothing is scored, and nothing a child does here is recorded or sent anywhere. It also has its own link, so you can send it to a child without sending them anywhere else first.
Is it calculate area they find hard, or telling it apart from calculate perimeter?
Those two look like one weakness on a practice paper and need completely different practice. A free diagnostic tells them apart across all four subjects.
