Fractions with objects (2,3,4,5)

Lesson

We have looked at fractions on fraction bars, fractions on a number line and fractions of shapes. However, fractions can also be used to divide a collection of items. To do this we use the:

• denominator to divide the items into equal groups
• numerator to select the number of groups

Remember!

If you get stuck with finding out how many items should be in each group, you can organise the items into an array to help to visualise the fraction parts. Watch the video above to find out more.

Unit fractions

When we only select one of the groups (so the numerator is one) it is called a unit fraction.

For example, to find $\frac{1}{4}$14 of $20$20 items, we divide the collection into four equal groups ($5$5 in each group) and then select one of them. Like this:

Try this question for yourself:

Worked example

Question 1:

Which of the following shows that $\frac{1}{3}$13 of these ice creams have been selected?

1. A

B

C

A

B

C

Non-unit fractions

We can also select more than one group which we would write as a non-unit fraction. This is where the numerator (top number) is larger than $1$1.

For example, to find two thirds ($\frac{2}{3}$23) of $12$12 items, we use the denominator to divide the items into equal groups (three equal groups) and then we select two of the groups.

Like this:

When we divide the twelve boats into three equal groups, there are four in each group. We then select two of the groups, eight boats, to represent two-thirds. Therefore, $\frac{2}{3}$23 of $12=8$12=8

Try this question for yourself:

Worked example

Question 2:

Which of the following shows that $\frac{2}{5}$25 of these trees have been selected?

1. A

B

C

A

B

C

Remember!

We use the denominator to divide the collection into equal groups.

We use the numerator to select the number of groups.