3
Fractions of a group
Discover Mathematics P2: Term 2, Lessons 101–110
GoalFind a fraction of a group of objects by splitting the group into equal sets.
New words
set · a group of thingsequal groups · groups with the same number of thingsof · 'half of 8' means one of the 2 equal groups of 8
Explanation
A fraction can name part of a group of things. To find 1/2 of 8 apples, split the 8 apples into 2 equal groups: 4 and 4. One group is the half, so 1/2 of 8 = 4. To find 1/4 of 8, split into 4 equal groups of 2. One group is 2, so 1/4 of 8 = 2. To find 1/3 of 6, split into 3 equal groups of 2, so 1/3 of 6 = 2. The bottom number tells how many equal groups to make.
Worked examples
8 apples in 2 equal groups of 4. One group is a half: 1/2 of 8 = 4.
8 balls in 4 equal groups of 2. One group is a fourth: 1/4 of 8 = 2.
6 flowers in 3 equal groups of 2. One group is a third: 1/3 of 6 = 2.
Class activity
Share the beans. Count 12 dried beans. Make 2 equal groups and say how many are in 1/2 of 12. Put them back and make 3 equal groups: how many in 1/3 of 12? Then make 4 equal groups: how many in 1/4 of 12? Write the three answers.
Practice
1
Find 1/2 of 10.
10 split into 2 equal groups is 5 and 5, so 1/2 of 10 = 5.
2
There are 9 bugs in 3 equal groups. How many bugs are 1/3 of 9?
1/3 of 9 = 3 bugs.
3
Find 1/4 of 12 pencils.
12 pencils in 4 equal groups of 3, so 1/4 of 12 = 3 pencils.
4
Salma has 6 stickers. She gives half of them to her friend. How many stickers does she give?
1/2 of 6 = 3 stickers.
5
Which is more: 1/2 of 8 or 1/4 of 8?
1/2 of 8 is 4 and 1/4 of 8 is 2, so 1/2 of 8 is more.