3
Story sums to 20
Joyful Mathematics: Chapter 6
GoalChoose to add or take away in a story, and solve two-step stories.
New words
join · put together, so we addgo away · taken away, so we subtracthow many were taken · find the missing number
Explanation
Read a story slowly. Ask: do things join, or do they go away? Join means add. Go away means take away. Some stories have two steps. Do one step at a time. Fatima has 8 kites. She gives away 3. Then she buys 6 kites. 8 − 3 = 5. 5 + 6 = 11.
Worked examples
A bakery has 16 biscuits. 9 are sold. How many are left? 16 − 9 = 7.
Tenzin has 13 marbles. He gives some to a friend. He has 8 left. How many did he give? Count back from 13 to 8: 5 steps. 13 − 5 = 8.
A tailor has 14 buttons. He sews 6 buttons on a shirt. 14 − 6 = 8 buttons are left.
Class activity
Shop story. Set up a pretend shop with 10 small things on a table. The grown-up tells a story: "You have 10. You sell 4. Then 3 more arrive." The child moves the things and says how many there are at each step: 6, then 9.
Practice
1
A flower seller has 18 roses. She sells 9. How many roses are left?
9. 18 − 9 = 9.
2
Sana has 9 sweets. Her aunt gives her 7 more. How many sweets now?
16.
3
Vihaan picks 12 flowers. He gives some to his grandmother. 9 are left. How many did he give her?
3. 12 − 3 = 9.
4
How many ducks are left?
11.
5
Kiran has 5 stickers. He gets 7 more. Then he gives 4 to his sister. How many stickers does he have now?
8. 5 + 7 = 12. 12 − 4 = 8.