8. Measurement

Lesson

We can work out the area of a shape by seeing how many squares fit inside it. Try this question.

Find the area of the shape by counting the number of grid squares it covers.

Each grid square represents 1 square unit.

Worked Solution

Idea summary

To find the area of a shape on a grid, we can count the number of unit squares inside the shape.

When we compared length , we looked at which object was **shorter**, or **longer** than the other. We used number lines or lines to help us do this. We can do a similar thing with **area**, but instead of lines, we use **squares**.

When we compare area, we can use a square unit to do this. So if we are working with centimetres, we use a square measuring 1\text{ cm} \times 1\text{ cm}. We can use the same method if we working with metres, but instead using a 1\text{ m} \times 1\text{ m} square.

In this video, we'll compare some shapes using a 1\,cm unit square.

Look at the two shapes on the grid.

a

What are the areas of Shape A and Shape B?

Worked Solution

b

Which is the smallest shape?

Worked Solution

Idea summary

To compare areas in the same units, we can compare the size of the numbers.

In this video we look at the area of objects in our everyday life, and how we might compare them. Which unit square should we use? What if we were to use a sheet of paper? Let's find out what happens when we do.

Caitlin's vegetable garden is 54 \text{ m}^2. Her flower garden is 27 \text{ m}^2. Which garden is smaller?

Worked Solution

Idea summary

We can use number lines to compare the size of areas of every day objects.

If both our **values** (numbers) and **units of measurement** are different, we can use what we know about a unit square to help work out which shape might have the largest area.

Which of these is the larger area?

A

40\text{ cm}^2

B

40\text{ m}^2

Worked Solution

Idea summary

When comparing the area of objects, don't just compare the numbers. Remember to compare the units of measurement as well.

Compare objects using familiar metric units of area and volume

Compare the areas of regular and irregular shapes by informal means