1. Addition and Subtraction Know addition and subtraction facts
Missing numbers
Objectives
Day 1
Know pairs to 10, and then to 7, 8 and 9.
Day 2
Know pairs to 20.
Day 3
Know pairs to 10 and 20, and write related addition and subtraction facts.
Before teaching, be aware that:
On Day 1 ideally you will need a real number balance. Alternatively use an interactive balance such as the one at
On Day 2 ideally you will need a real 20 bead frame (with two rows of beads). Alternatively use the slides.
On Day 3 children will need mini-whiteboards and pens. You may wish to use real interconnecting cubes (blue, red and yellow).
Year 2

2. Addition and Subtraction Know addition and subtraction facts
Missing numbers
Starters
Day 1
Pairs to 10 (pre-requisite skills)
Day 2
Say one more or one less than any 2-digit number (simmering skills)
Day 3
Place value in 2-digit numbers (simmering skills)
Choose starters that suit your class by dragging and dropping the relevant slide or slides below to the start of the teaching for each day.
Year 2

3. Addition and Subtraction Know addition and subtraction facts
Missing numbers
Starter
Pairs to 10
Pre-requisite skills – to use this starter, drag this slide to the start of Day 1
Show 10 pegs (5 in one colour and 5 in another) on a coat hanger. How can we split 10 into 2 groups? Take one suggestion, e.g. 8 and 2, and split the pegs into a group of 8 and a group of 2. Record Turn the coat hanger round to show Challenge children to work in pairs to write all the pairs to 10. Do they remember and/ or ?
Year 2

4. Addition and Subtraction
Know addition and subtraction facts
Missing numbers
Starter
Say one more or one less than any 2-digit number
Simmering skills – to use this starter, drag this slide to the start of Day 2
Display a 1 to 100 grid. Shuffle a set of 10 cards, each with a 2-digit number (including numbers such as 50 and 29). Show one to the class. Half the class write the number that is 1 more and the other half write the number that is 1 less. Check on the 100 grid. Repeat with the next 4 cards, then ask the opposite halves of the class to write 1 more and 1 less for the remaining cards.
Year 2

5. Addition and Subtraction
Know addition and subtraction facts
Missing numbers
Starter
Place value in 2-digit numbers
Simmering skills – to use this starter, drag this slide to the start of Day 3
Show 42 beads on the 100-bead bar. Children work in pairs to hold up the correct place value cards to match, repeat with other numbers including 19 and 91, 15 and 51, 27 and 72 for example. Call out ‘no-work’ sums (place value additions), e.g. 70 add 3, 60 add 2. Children hold up PV cards to answer as quickly as they can!
Year 2

6. Addition and Subtraction Know addition and subtraction facts
Missing numbers
Objectives
Day 1
Know pairs to 10, and then to 7, 8 and 9.
Year 2

7. Hang weights on the number balance, 6 on one side and 10 on the other.
Day 1: Know pairs to 10, and then to 7, 8 and 9.
Hang weights on the number balance, 6 on one side and 10 on the other.
Where should I hang it?
If I hang an extra weight on the left side it will balance.
Show children a real number balance. Alternatively use the interactive balance at clicking the picture above to follow the link.
Hang weights on the number balance, 6 on one side and 10 on the other.
Try children’s suggestions until you balance 6 and 4 with 10.
= 10 4
Year 2

8. How could we make it balance?
Day 1: Know pairs to 10, and then to 7, 8 and 9.
Hang weights:
6 on one side, and 9 and 1 on the other.
How could we make it balance?
What happens?
6 and 4 balance 9 and 1.
Hang weights on the number balance, 6 on one side, and 9 and 1 on the other.
Try children’s suggestions and agree that hanging 4 on the left would make it balance.
= 9 + 1 4
Year 2

9. What can I do to the other side so it balances?
Day 1: Know pairs to 10, and then to 7, 8 and 9.
Move the weight on 1 to 2.
What can I do to the other side so it balances?
What happens?
Move the weight from 1 to 2.
Try children’s suggestions and agree for example that moving the weight from 4 to 5 will make the sides balance.
6 and 5 balance 9 and 2.
= 9 + 2 5
Year 2

10. Where shall we hang a weight this time to balance?
Day 1: Know pairs to 10, and then to 7, 8 and 9.
Hang weights:
7 and 3 on one side, and 8 on the other.
Where shall we hang a weight this time to balance?
Hang weights on the number balance, 7 and 3 on one side, and 8 on the other.
Try children’s suggestions and agree that hanging 2 on the right would make it balance.
7 and 3 balance 8 and 2.
7 + 3 = 8 + 2
Year 2

11. Where shall we hang a weight this time to balance?
Day 1: Know pairs to 10, and then to 7, 8 and 9.
Hang weights:
5 and 3 on one side, and 6 on the other.
Where shall we hang a weight this time to balance?
Hang weights on the number balance, 7 and 3 on one side, and 8 on the other.
Try children’s suggestions and agree that hanging 2 on the right would make it balance.
5 and 3 balance 6 and 2.
5 + 3 = 6 + 2
Year 2

12. Where shall we hang a weight this time to balance?
Day 1: Know pairs to 10, and then to 7, 8 and 9.
Hang weights:
7 and 1 on one side, and 4 on the other.
Where shall we hang a weight this time to balance?
Hang weights on the number balance, 7 and 3 on one side, and 8 on the other.
Try children’s suggestions and agree that hanging 2 on the right would make it balance.
7 and 1 balance 4 and 4.
7 + 1 = 4 + 4
Year 2

13. The Practice Sheet on this slide is suitable for most children.
Differentiated PRACTICE WORKSHEETS are available on Hamilton’s website in this unit’s PROCEDURAL FLUENCY box.
WT: Addition and subtraction Sheet 1 – add bricks to make a total of 10.
ARE: Addition and subtraction Sheet 2 – write pairs with a total of 10.
GD: Addition and subtraction Sheet 3 – write three numbers with a total of 10.
Challenge
Year 2

14. Addition and Subtraction Know addition and subtraction facts
Missing numbers
Objectives
Day 2
Know pairs to 20.
Year 2

15. How many beads are there on each bar?
Day 2: Know pairs to 20.
How many beads are there on each bar?
Use a 20 bead frame or the slide above.
And altogether?
Year 2

16. 15 + = 20 5 Day 2: Know pairs to 20. How many have I hidden?
What colour are they? How many were on the bottom row?
What do you add to 5 to make 10?
How do you know?
= 20 5
Year 2

17. 18 + = 20 2 Day 2: Know pairs to 20. How many have I hidden?
What colour are they? How many were on the bottom row?
What do you add to 8 to make 10?
How do you know?
= 20 2
Year 2

18. 16 + = 20 4 Day 2: Know pairs to 20. How many have I hidden?
What colour are they? How many were on the bottom row?
What do you add to 6 to make 10?
How do you know?
= 20 4
Year 2

19. 14 + = 20 6 Day 2: Know pairs to 20. How many have I hidden?
What colour are they? How many were on the bottom row?
What do you add to 4 to make 10?
How do you know?
= 20 6
Year 2

20. Day 2: Know pairs to 20.
If we know 7 add 3 makes 10, what do we add to 17 to make 20?
What do we add to 13 to make 20? How do you know?
Children can now go on to do differentiated GROUP ACTIVITIES. You can find Hamilton’s group activities in this unit’s TEACHING AND GROUP ACTIVITIES download.
WT/ARE/GD: Children find missing numbers to create a pair of numbers that add up to 20.
= 20 3
= 20 7
Year 2

21. Challenge
The Practice Sheet on this slide is suitable for most children.
Differentiated PRACTICE WORKSHEETS are available on Hamilton’s website in this unit’s PROCEDURAL FLUENCY box.
WT: Pairs to 10 and 20 Sheet 1 – add bricks to make 10, then 20.
ARE: Pairs to 20 Sheet 2.
GD: Pairs to 20 Sheet 3 – draw bar models for pairs to 20.
Year 2

22. Addition and Subtraction Know addition and subtraction facts
Missing numbers
Objectives
Day 3
Know pairs to 10 and 20, and write related addition and subtraction facts.
Year 2

23. Day 3: Know pairs to 10 and 20, and write related addition and subtraction facts.
This picture shows that 6 and 4 cubes is the same amount as 10 cubes.
6 + 4 = 10
We could have the 4 cubes first and then the 6 cubes, and this would still give 10 cubes altogether!
4 + 6 = 10
Year 2

24. Day 3: Know pairs to 10 and 20, and write related addition and subtraction facts.
If we took away the 4 cubes, how many cubes would be left?
10 – 4 = 6
What if we took away the 6 cubes instead?
10 – 6 = 4
Year 2

25. Day 3: Know pairs to 10 and 20, and write related addition and subtraction facts.
We can write 4 number sentences to go with this one picture!
6 + 4 = 10
4 + 6 = 10
10 – 4 = 6
10 – 6 = 4
Year 2

26. Day 3: Know pairs to 10 and 20, and write related addition and subtraction facts.6 4
It can be time consuming to draw all the cubes, so we can just draw bars to represent the cubes.
Year 2

27. Day 3: Know pairs to 10 and 20, and write related addition and subtraction facts.5
With a partner, write an addition and a subtraction to go with this picture.
5 + 5 = 10
10 – 5 = 5
Year 2

28. Day 3: Know pairs to 10 and 20, and write related addition and subtraction facts.
Let’s write number sentences to go with this picture. 20 16 4
= 20
= 20
20 – 4 = 16
20 – 16 = 4
Children can now go on to do differentiated GROUP ACTIVITIES. You can find Hamilton’s group activities in this unit’s TEACHING AND GROUP ACTIVITIES download.
WT: Children use bar models to create pairs of numbers that add up to 10, using inverse operations.
ARE/GD: Children use bar models to create pairs of numbers that add up to 10 and 20, using inverse operations.
Year 2

29. Challenge Pairs to 20 Sheet 2
Write the missing number in each bar model. 20 11 20 13 20 5 20 16 20 7 20 12 20 9 20
The Practice Sheet on this slide is suitable for most children.
Differentiated PRACTICE WORKSHEETS are available on Hamilton’s website in this unit’s PROCEDURAL FLUENCY box.
WT: Pairs to 10 and 20 Sheet 1 – complete bar models to 10, then 20.
ARE: Pairs to 20 Sheet 2 – complete bar models to 20.
GD: Missing numbers Sheet 3 – complete bar models with trios to 20.
Challenge
Year 2

30. Addition and Subtraction Know addition and subtraction facts
Missing numbers
Well Done! You’ve completed this unit.
Objectives
Day 1
Know pairs to 10, and then to 7, 8 and 9.
Day 2
Know pairs to 20.
Day 3
Know pairs to 10 and 20, and write related addition and subtraction facts.
You can now use the Mastery: Reasoning and Problem-Solving questions to assess children’s success across this unit. Go to the next slide.
Year 2

31. Problem solving and reasoning questions
Write the pairs of possible missing numbers.
How many different ways are there of writing numbers in the two boxes in this sentence?
☐ +  = 10
What if the total of the two missing numbers = 9? Or = 8?
You have 21 cards: 0 to How many pairs of numbers can you create which make 20? Write these.
Write the pair you cannot create. 20 11 ?
Year 2

32. Problem solving and reasoning: Answers
Write the pairs of possible missing numbers.
The missing pair of numbers adds to 9… (or 4 + 5); (or 3 + 6); (or 2 + 7); (or 1 + 8);
9 + 0 (or 0 + 9). Errors may arise when children fail to recognise 9 as the difference between 20 and 11.  
For this, and the following questions, consider how systematically children have listed the possibilities and challenge them to do so if they have missed some of the answers.
How many different ways are there of writing numbers in the two boxes in this sentence?
☐ +  = possibilities , 9 + 1, … 1 + 9,
What if the total of the two missing numbers = 9? Or = 8?
10 possibilities if the total is 9; 9 possibilities if the total is 8.
You have 21 cards: 0 to How many pairs of numbers can you create which make 20? Write these.
10 pairs: , , , , , , , , ,
Write the pair you cannot create. The missing pair is (since there is only one 10 card). 20 11 ?
Year 2