4
Putting halves together
Learner’s Book 1: Unit 11, pp. 162–164
GoalPut halves together to make wholes and find half of even numbers up to 20.
New words
halve · share into 2 equal partshalf of a number · the number shared equally into 2 groupswhole · all of something
Explanation
Two halves make one whole. So 6 half oranges make 3 whole oranges. We can halve numbers too. To find half of a number, share it equally into 2 groups. Half of 6 is 3. Half of 12 is 6. Half of 16 is 8. Counters help: share them one at a time into 2 groups. If you share equally between 2 people, each person gets half.
Worked examples
6 half oranges make 3 whole oranges, because 2 halves make 1 whole. Each circle shows 2 halves put together.
To find half of 20, share 20 counters into 2 equal groups. Each group has 10. Half of 20 is 10.
| Ravi | Zara | |
|---|---|---|
| plums | 4 | 4 |
| nuts | 3 | 3 |
Class activity
Counter halving: put out 2 cups and 20 counters. Pick a number from 2 to 20 (even numbers work best). Count out that many counters and share them one by one into the 2 cups. How many in each cup? That is half the number.
Practice
1
You have 10 half pears. How many whole pears can you make?
5 (2 halves make 1 whole pear)
2
Use the counters to find half of 12.
6
3
What is half of 14?
7
4
Zara has 18 stickers. She gives half to her sister. How many does her sister get?
9