Area by counting squares
The area of a shape is the size of its two dimensional surface.
When a square measures 1 cm by 1 cm, we say it has an area of 1 cm2 (centimetre squared).
This rectangle covers 15 squares so it has an area of 15 cm2.
To find the exact area of a shape, count the whole squares and half squares.
Question
Calculate the exact area of the shape shown on a 1 cm square grid.
11 陆 cm2
There are eight whole squares = 8 cm2 and seven half squares = 3 陆 cm2.
Sometimes the shape doesn鈥檛 fit exactly on the grid. We can estimate the area by counting the squares that are halfway or more. Mark each square that you have included so that you don鈥檛 count it twice (and to show an examiner that you have counted the squares). You may also want to note every multiple of ten in case you lose count.
Question
The shape, drawn on a square grid, represents an island. By counting squares, estimate the area of the island when every square represents 5 m2.
By counting every square that is half or more we see that the shape covers approximately 40 squares. As each square represents 5 m2, we multiply 40 by 5 to find the area of the island is approximately 200 m2.
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