 Do you know what would be a suitable unit to measure the area of a classroom?

# Perimeter and Area (Year 4)

In KS2 Maths children will come to understand both perimeter and area. In Year Four children will learn how to work out the perimeter of a square or a rectangle and how to calculate the length of the sides in a square from its perimeter. They will also be introduced to the correct units to use (mm2 cm2 or m2) when measuring area and asked to make realistic estimates of a shape's area.

When measuring a 2D shape, like a square or a rectangle, it is useful to know what the perimeter and area of a shape are. The perimeter is the total distance around the outside of a two-dimensional shape. Area is the amount of space covered by the shape's surface. To work out the area of a rectangle multiply the length of its longest side by the length of its shortest side. This will give you an answer in square mm, cm or m (mm2 cm2 or m2).

Take this quiz for 8-9 year olds to discover what you know about area and perimeter.

1.
Which is a good estimate of the perimeter of a mobile 'phone?
100cm
34cm
2m
25mm
100cm = 1m That's way too big for a 'phone!
2.
What is the perimeter of a 6cm square?
6cm
12cm
18cm
24cm
A square has four equal sides, therefore the perimeter will be 4 x 6 = 24
3.
What is the perimeter of a rectangle 5cm x 9cm?
14cm
20cm
28cm
45cm
A rectangle has two sides of equal length and two more side with equal length. So the answer is:
(2 x 5) + (2 x 9) which is
10 + 18 = 28
4.
What is useful to work out the area of a small 2D shape?
Tracing paper
Measuring jug
Metre stick
Squared paper
Squared paper helps to work out the area of irregular shapes too
5.
Which would be a suitable unit to measure the area of a classroom?
Square metres
Square millimetres
Square centimetres
Square kilograms
Millimetres and centimetres would be way too small and kilograms measure weight!
6.
What is a perimeter?
The distance around the edge of a shape
The distance across a shape
The size of the surface of a 2D shape
The size of the surface of a 3D shape
To calculate the perimeter of a 2D shape, add together the length of each side
7.
Which would be a good estimate of the area of a small notebook?
1,000cm2
5cm2
26cm2
500cm2
This would be a very small notebook measuring 4cm x 6.5cm
8.
What is area?
The distance around the edge of a 2D shape
The distance across a 2D shape
The size of the surface of a 2D shape
The distance around the edge of a 3D shape
Area is measured in square mm cm m or km
9.
A square has a perimeter of 32cm. How long are the sides?
4cm
8cm
10cm
16cm
As a square has four equal sides, we divide by 4 to get the answer
10.
How is square centimetre usually written?
Cm sq
Sq cm
cm2
2cm
Cubed cm are written as cm3
You can find more about this topic by visiting BBC Bitesize - How to work out an area

Author:  Amanda Swift 