Lesson 16 — Activity 1:

Measuring the Perimeter of Regular Shapes

In this first activity in the Everyday Measurement theme, you will learn to find the perimeter of different objects.

So, what is perimeter and how can we use perimeter in our everyday lives?

Perimeter is the distance all the way around the outside of a two-dimensional shape.

Some examples of how perimeter is used in our lives and in our jobs are:
 

a police officer who measures the scene of an accident

an electrician who uses measurement to string the wire in homes and buildings

a contractor (or maybe yourself) who measures around a basement to cut the wood in order to finish it

So how do we find perimeter?

If a figure has straight sides, the lengths, or number of units of its sides, are added to find the perimeter. In the example below, the "P" stands for perimeter, and the "S" stands for "side."

Notice that the spelling of perimeter is different than the metric system spelling of metre. 

Here is an example of how to find the perimeter of a square with straight sides.

Let's say that you have a job installing windows in new homes. You need to find the perimeter of a window that will go in the basement of a house. Before you can install the window, you need to measure around the outside of the window (the perimeter).

If each side on the window is 6 units, all you need to do is add the four sides together to find the perimeter.

Perimeter = 6 + 6 + 6 + 6 = 24 units