Area

In the last chapter, you measured lengths in centimetres and metres. 1 centimetre is about the width of a fingertip. Today, we will find the area of a figure by counting square units. Lin draws a tile pattern on a grid. Each small square has an area of 1 square centimetre. Find the area of her shaded pattern. The area of a figure is the amount of surface it covers. Each small square is 1 square centimetre. We write 1 square centimetre like this. Its sides are 1 centimetre long, about the width of a fingertip. Count the whole squares in the top row: 1, 2. Now the middle row: 1, 2, 3, 4. And the bottom row: 1, 2. 2 plus 4 plus 2 is 8 whole squares. There are also 2 half squares. Two half squares make 1 whole square. 2 divided by 2 is 1 whole square. 8 plus 1 is 9, so the figure covers 9 squares. Each square is 1 square centimetre, so the area is 9 square centimetres. Bigger areas, like a floor, are measured in square metres.

A walkway is covered with square tiles. Each tile has an area of 1 square metre. Find the area of the shaded part. Try it first. Pause if you like. Each tile is 1 square metre, a square with sides of 1 metre. We write 1 square metre like this. 1 metre is about one big step. Count the whole squares row by row: 2, 5 and 4. 2 plus 5 plus 4 is 11 whole squares. Each square is 1 square metre, so the area is 11 square metres.

Lin shades another figure on a grid. Each small square has an area of 1 square centimetre. Find the area of the shaded figure. Try it first. Pause if you like. Count the whole squares row by row: 4, 3 and 2. 4 plus 3 plus 2 is 9 whole squares. Now count the half squares: 1, 2, 3, 4, 5, 6. Two half squares make 1 whole square, so 6 divided by 2 is 3. 9 plus 3 is 12, so the figure covers 12 squares. So the area is 12 square centimetres. Each half square counts as half, never as a whole. Area counts the square units a figure covers. Two half squares make one whole square.