Walking Around Rectangles: Finding the Perimeter

Imagine you are a tiny ant walking all the way around the edge of your desk without stopping. The total distance you walk is called the perimeter. Before we start, think about this: if your desk is shaped like a rectangle, how many sides does it have? And does a rectangle have any sides that are equal to each other?

The perimeter of a shape is the total distance around its outside edge. Think of it as measuring the fence around a garden. A rectangle has four sides. The two longer sides are called the length. The two shorter sides are called the width. In a rectangle, opposite sides are always equal — the two lengths are the same, and the two widths are the same. To find the perimeter, you add up all four sides: Perimeter = length + width + length + width Because the two lengths are equal and the two widths are equal, you can also write it as: Perimeter = (2 × length) + (2 × width) The × symbol means 'multiply' or 'times'. The ( ) brackets just mean 'work this part out first'. We measure perimeter in units of length, like centimetres (cm) or metres (m).