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Australia
Year 4

8.03 Identify fractions in areas

Lesson

Are you ready?

Can you recognise the number of equal parts and what fraction that makes?

Examples

Example 1

Here is a shape divided into parts, use it to answer the following questions.

A triangle divided in 3 equal parts.
a

This shape has ⬚ equal parts.

Worked Solution
Create a strategy

Count the number of smaller parts.

Apply the idea

This shape has 3 equal parts.

b

Each part is \dfrac{⬚}{⬚} of the whole.

Worked Solution
Create a strategy

Write each part as a fraction: \,\,\dfrac{\text{Number of shaded parts}}{\text{ Total number of parts}}

Apply the idea

Each part looks like this shaded part.

A triangle divided in 3 equal parts and 1 part is shaded.

We have 3 parts and we only want 1 of them.

Each part is \dfrac{1}{3} of the whole.

Idea summary

When using area models we can write each part as a fraction: \dfrac{\text{Number of shaded parts}}{\text{ Total number of parts}}

Shapes and fractions

When we divide shapes into equal parts, we have seen how the parts can be described using fractions. We can also use this to describe the area of part of our shape.

The image shows 3 different shapes divided into equal parts, where some are shaded. Ask your teacher for more information.

We can divide shapes up into parts and describe these parts as fractions. We can also use this to describe the area of a part of our shape.

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Examples

Example 2

Which of the following shows \dfrac{2}{6} of the area shaded?

A
A fraction bar divided into 6 equal parts. Two parts are shaded.
B
A fraction bar divided into 8 equal parts. Two parts are shaded.
Worked Solution
Create a strategy

The top part of the fraction (numerator) tells us how many parts of the shape should be shaded. The bottom part of the fraction (denominator) tells us how many parts to divide the shape up into.

Apply the idea

The fraction \dfrac{2}{6} is asking for two parts of the shape to be shaded. So 2 out of 6 parts should be shaded. This means that the correct answer is Option A.

Idea summary

If our shape doesn't have equal parts, we can still estimate the area for parts of our shape.

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