Programme 7: Patterns of subtraction
- Developing knowledge of number bonds as subtraction facts
- Recognising that subtraction is the inverse of addition
- Recognising patterns in subtraction and using these to predict answers
- Subtracting single digit numbers from multiples of ten
Vocabulary: take away, minus, subtract, subtraction fewer, less than, count back
Resources: Fill the boats activity sheet, die numbered 4 - 9
It is useful to make links with programme 2 and related activities (patterns in addition).
Patterns in addition and subtraction Whole class or group activity
Talk about Brad Quiff and the Punch and Judy show. Show the children the number sentence:
7 - ____ = 4 Ask them to explain how they can work out what number should go into the box to make the number sentence true. Encourage them to use their knowledge of number bonds (4 + 3 = 7) to work out the missing number. Talk about all the number sentences they can write using this knowledge:
4 + 3 = 7 7 - 4 = 3
3 + 4 = 7 7 - 3 = 4
Extend this to multiples of 10 and 100:
40 + 30 = 70 70 - 40 = 30 400 + 300 = 700 700 - 400 = 300
30 + 40 = 70 70 - 30 = 40 300 + 400 = 700 700 - 300 = 400
Hide some of the numbers using a post-it and ask the children to work out which number is hidden.
Fill the boats- Individual, paired or small group activities
Draw 6 or 7 boats on a sheet of A4 paper. In the boat write in a sum ___ + ___ = ___ . Roll a dice numbered 4 - 9 twice. The first number thrown tells you the number of tens of ants you have to start with and the second throw tells you how many single ants. Write this number at the top of the sheet.
The aim of the activity is to put ants in the boats with no more than 10 in each boat. Put 10 ants into the first boat and work out how many ants you have left. Write a number sentence to show how you worked it out. Continue to put 10 ants into each boat, writing a number sentence each time. Are there 10 ants in each boat? Do any boats have less than 10 ants? Can you fill all the boats? Are there any ants without a boat?
Arrange all the ants in the boats so that all the boats have some ants in and all the ants are in a boat. Try and arrange the ants so that there are almost the same number in each boat. Write a number sentence on each boat to show how many remain each time.