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Grade 4

Areas of regular and irregular shapes

Lesson

Area

We can measure area in shapes such as squares and rectangles, but what about different shapes? 

To help us measure the area of shapes like the ones pictured below, we can use square units.

In Video 1, we calculate the area of shapes similar to those in the picture above. We also look at shapes where we know the unit of measurement.

 

How to count square units

Sometimes we have unusual shapes but we can still work out the area of these shapes by counting the number of square units inside. We can also work out the area of triangles! See how we do this in Video 3.

Did you know?

We can use square units to measure the area of something really large, such as rooms in a house, without needing to draw things the actual size!

 

Worked Examples

Question 1

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

Each grid square represents $1$1 square unit.

Question 2

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

Each grid square represents $1$1 square unit.

Question 3

Look at the two shapes laid on the grid.

  1. Fill in the gaps below.

    The area of Shape A is $\editable{}$ square units.

    The area of Shape B is $\editable{}$ square units.

  2. Which is the smallest shape?

    Shape A

    A

    Shape B

    B

Outcomes

4.M1.05

Estimate, measure using a variety of tools (e.g., centimetre grid paper, geoboard) and strategies, and record the perimeter and area of polygons

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