Area is how much surface a shape covers. On a grid of 1 cm squares, count the squares the shape covers, row by row, so none are missed. Count only the shaded squares, not the edges around the shape (that is the perimeter). Two half squares make one whole square, so count the halves and share them into pairs. A right-angled triangle is half of the rectangle drawn around it.
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Maths you can move
Build 8 + 5
Tap two gold counters to fill the ten-frame.
8 in the frame + 5 waiting. The total stays the same.
Words to know
- area
- the amount of surface a shape covers
- square centimetre (cm²)
- the area of a square 1 cm long and 1 cm wide
- half square
- a square cut in half along its diagonal
Worked examples
A shaded shape has rows of 3, 4 and 2 squares. What is its area?
- 1.Count row by row.
- 2.3 + 4 + 2 = 9 squares.
= 9
A shape covers 6 whole squares and 4 half squares. What is its area?
- 1.4 half squares make 2 whole squares.
- 2.6 + 2 = 8 cm².
= 8
A 3 by 2 rectangle has a right-angled triangle on top with sides of 2 and 3 squares. What is the area?
- 1.The rectangle is 3 × 2 = 6 squares.
- 2.The triangle is half of 2 × 3 = 6, so 3. 6 + 3 = 9 cm².
= 9
For parents
Method: Count squares, pair the halves
What to say: Did you count every shaded piece once? How many halves make a whole?
Common mistakes:
- Counts the unit edges around the outside of the shape (its perimeter) instead of the squares inside.
- Counts every square in the rectangle around the shape, including unshaded squares.
- Counts the grid points (the corners of the squares) instead of the squares themselves.
- Counts each half or part square as a whole square.
- Counts only the whole squares and leaves out the half or part squares.
- Adds 'and a half' once for all the half squares, instead of half for each one.
- Counts the triangle as the whole rectangle around it, forgetting that a right triangle is half of that rectangle.