12
Subtraction
Textbook Part 1, pp. 26–27
GoalUnderstand taking part of a group away as subtraction; read the “−” sign.
New words
subtraction · ayirishminus (−) · minus (−)difference · ayirmawere left · qoldi
Explanation
When some objects are taken away from a group, we subtract. There were 5 children in the class, 2 left — 3 stayed: 5 − 2 = 3. We read it “five minus two equals three”. The result is called the difference.
Worked examples
🎈🎈🎈🎈 — 1 balloon flew away: 4 − 1 = 3.
There were 6 cherries on a plate and 2 were eaten: 6 − 2 = 4.
Class activity
Put 5 blocks on the table. One child closes their eyes while another hides some. The first child works out how many were hidden and says the number sentence.
Practice
1
🍪🍪🍪🍪 − 🍪 = ?
3
2
5 − 2 = ?
3
3
6 − 3 = ?
3
4
There were 7 apples on a tree. 2 fell down. How many are left?
5