Perimeter and area

For grown-ups: this lesson in words

Years 3 to 6 · Maths

Perimeter and area: I can find the perimeter and the area of a shape.

1. Here is a rectangle on squared paper. Each square is 1 cm long.

   The long side is 5 squares, so it is 5 cm.

   The short side is 3 squares, so it is 3 cm.

   The perimeter is the distance all the way round the outside edge.

   Picture: A squared grid numbered 0 to 8 along and up. A shape with 4 corners: 1 square along and 1 square up; 6 squares along and 1 square up; 6 squares along and 4 squares up; 1 square along and 4 squares up.

2. Walk round the edge and add every side: 5 cm, 3 cm, 5 cm and 3 cm.

   5 + 3 + 5 + 3 = 16

   The perimeter is 16 cm.

   A quick way: double 5 and double 3. 10 + 6 = 16

   Picture: A squared grid numbered 0 to 8 along and up. A shape with 4 corners: 1 square along and 1 square up; 6 squares along and 1 square up; 6 squares along and 4 squares up; 1 square along and 4 squares up.

3. Your turn: Each square is 1 cm. This rectangle is 4 cm long and 2 cm tall. What is its perimeter?

   Picture: A squared grid numbered 0 to 6 along and up. A shape with 4 corners: 1 square along and 1 square up; 5 squares along and 1 square up; 5 squares along and 3 squares up; 1 square along and 3 squares up.

   Choose one:

   • 6 cm
   • 8 cm
   • 12 cm

   Answer

   The answer: 12 cm

   4 + 2 + 4 + 2 = 12. The perimeter is 12 cm.

Words to know

perimeter:

The distance all the way round the edge of a shape.

area:

The space inside a shape, measured in squares.

square centimetre:

A square that is 1 cm long and 1 cm tall. We write it cm².

base:

The side a triangle or a parallelogram stands on.

height:

How tall a shape is, measured straight up from the base.