1. Addition and Subtraction Add 10s and near 10s to a 2-digit number
Objectives
Day 1
Adding 10s to a 2-digit number.
Day 2
Adding near 10s to a 2-digit number.
Before teaching, be aware that:
On Day 1 children will need mini-whiteboards and pens. You will need ‘+10’ & ‘- 10’ cards, bean-bag.
On Day 2 children will need mini-whiteboards and pens. You will need ‘+10’ & ‘- 10’ cards, number grid (see resources), plastic Spider and Fly.
Year 1

2. Addition and Subtraction Add 10s and near 10s to a 2-digit number
Starters
Day 1
Count on and back in 10s (pre-requisite skills)
Day 2
Count in 10s from single-digit numbers (pre-requisite 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 1

3. Addition and Subtraction Add 10s and near 10s to a 2-digit number
Starter
Count on and back in 10s
Pre-requisite skills – to use this starter, drag this slide to the start of Day 1
Use a number grid (see starters resources) to support counting on in 10s from 0 to 100 and back again – show Spider going down and up the grid. Hold up a card showing +10. Pass a bean bag round the class as you count on in 10s from 10. Shout change, show –10 and pass it back again, counting back in 10s. Throw the bean bag to a child, saying 30. They say the number that is 10 more and throw back to you. Repeat with other multiples of 10.
Year 1

4. Addition and Subtraction
Add 10s and near 10s to a 2-digit number
Starter
Count in 10s from single-digit numbers
Pre-requisite skills – to use this starter, drag this slide to the start of Day 2
Count on in 10s from 5 on the 1–100 number grid (see starters resources) and back again as a whole class. Repeat without the grid.
Repeat from 8.
Hide the grid, show the number 3, show ‘+10’ card. Children count on in 10s. Turn card to show ‘–10’; they count back in 10s. Turn card back and forth, with children responding by counting in the appropriate direction. Change the starting number and repeat.
Year 1

5. Year 1

6. Addition and Subtraction Add 10s and near 10s to a 2-digit number
Objectives
Day 1
Adding 10s to a 2-digit number.
Year 1

7. Can you remember how spider helps us to add?
Day 1: Adding 10s to a 2-digit number.
Can you remember how spider helps us to add?
What is 21 add 10?
This saves us having to count on in 1s, so makes counting a lot quicker!
Year 1

8. When the count reaches 51 say STOP!
Day 1: Adding 10s to a 2-digit number.
Pass a bean bag around the circle, with children continuing to count on in 10s.
What is 10 more?
When the count reaches 51 say STOP!
51 add 10 is 61
= 61
Year 1

9. Can you show a number sentence for this?
Day 1: Adding 10s to a 2-digit number.
Can you show a number sentence for this?
On your whiteboards write 10 more than 61.
= 71
Year 1

10. This time we will start at 5 and count on in 10s.
Day 1: Adding 10s to a 2-digit number.
This time we will start at 5 and count on in 10s.
Repeat passing the bean bag around the circle with children continuing to count on in 10s.
When the count reaches 45 say STOP!
Year 1

11. 45 + 10 = 55 Day 1: Adding 10s to a 2-digit number.
On your whiteboards write 10 more than 45.
Can you show a number sentence for this?
= 55
Year 1

12. This time we are starting on 18 and counting on in 10s
Day 1: Adding 10s to a 2-digit number.
This time we are starting on 18 and counting on in 10s
This time when you pass the bean bag start at 18 with children continuing to count on in 10s.
When the count reaches 78 say STOP!
Year 1

13. 78 + 10 = 88 Day 1: Adding 10s to a 2-digit number.
On your whiteboards write 10 more than 78.
Can you show a number sentence for this?
= 88
Year 1

14. Where do you think Spider will land?
Day 1: Adding 10s to a 2-digit number.
What is
17 add 20?
Where do you think Spider will land?
= 37
Year 1

15. Where do you think Spider will land?
Day 1: Adding 10s to a 2-digit number.
Let’s try
26 add 20.
Where do you think Spider will land?
= 46
Year 1

16. Where do you think Spider will land?
Day 1: Adding 10s to a 2-digit number.
And how about
33 add 20?
Where do you think Spider will land?
= 53
Year 1

17. 58 + 20 = 78 Day 1: Adding 10s to a 2-digit number.
On your whiteboards write 20 more than 58.
Can you show a number sentence for this?
= 78
Year 1

18. Can you show a number sentence for this?
Day 1: Adding 10s to a 2-digit number.
Now write 20 more than 44.
Can you show a number sentence for this?
= 64
Year 1

19. Where do you think Spider will land?
Day 1: Adding 10s to a 2-digit number.
Now let’s try
14 add 30.
Where do you think Spider will land?
= 44
Year 1

20. 32 + 30 = 62 Day 1: Adding 10s to a 2-digit number.
On your whiteboards write 30 more than 32.
Can you show a number sentence for this?
= 62
Year 1

21. Where do you think Spider will land?
Day 1: Adding 10s to a 2-digit number.
Can we do 27 add 40?
Where do you think Spider will land?
Repeat with adding 20 to other starting numbers with, then without the grid.
Extend to adding 30 and 40 (not passing 100).
= 67
Year 1

22. 29 + 40 = 69 Day 1: Adding 10s to a 2-digit number.
On your whiteboards write 40 more than 29.
Can you show a number sentence for this?
= 69
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: Roll a dice to generate a number of 10s to add to a number. Add and record a number sentence.
GD: Work out the missing number in an addition number sentence.
Year 1

23. Year 1 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/ARE: Adding tens Sheet 1
GD: Adding tens Sheet 2
Year 1

24. Addition and Subtraction Add 10s and near 10s to a 2-digit number
Objectives
Day 2
Adding near 10s to a 2-digit number.
Year 1

25. How is this different to the number sentences from the last lesson?
Day 2: Adding near 10s to a 2-digit number. =
How is this different to the number sentences from the last lesson?
Year 1

26. Instead of adding 10 we are going to add 11…1 more than 10!
Day 1: Adding 10s to a 2-digit number.
Instead of adding 10 we are going to add 11…1 more than 10!
Let’s start by adding 10 though. What is 53 add 10?
Year 1

27. But we haven’t finished yet!
Day 1: Adding 10s to a 2-digit number.
But we haven’t finished yet!
We need to add 1 more.
Who can help us by adding across the grid?
Year 1

28. Let’s get fly to add 1 more.
Day 1: Adding 10s to a 2-digit number.
Fly!
Let’s get fly to add 1 more.
So what is ? 64
Year 1

29. Day 2: Adding near 10s to a 2-digit number.
= 64
Year 1

30. This time let’s try adding 11 to 30.
Day 1: Adding 10s to a 2-digit number.
This time let’s try adding 11 to 30.
What is 30 add 10?
Year 1

31. But we haven’t finished yet!
Day 1: Adding 10s to a 2-digit number.
But we haven’t finished yet!
We need to add 1 more.
We are at the end of the row so what should we do to add 1 more?
Year 1

32. We need to move Fly to the beginning of the next row!
Day 1: Adding 10s to a 2-digit number.
We need to move Fly to the beginning of the next row!
So what is ?
= 41
Year 1

33. Day 2: Adding near 10s to a 2-digit number.
Now it’s your turn! Tell your partner how to add 11 to 44.
Record your number sentences on whiteboards.
Then swap to explain how to add 11 to 38.
Choose a child to demonstrate what happens to Spider and Fly each time to reach the answer.
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: Work out the new price for the stationery after a price increase of 11p.
GD: Explore the 100 grid to add 11 to a range of numbers. Work backwards to find a starting number.
Year 1

34. Year 1 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/ARE/GD: Adding 11 Sheet 1
Year 1

35. Addition and Subtraction Add 10s and near 10s to a 2-digit number
Well Done! You’ve completed this unit.
Objectives
Day 1
Adding 10s to a 2-digit number.
Day 2
Adding near 10s to a 2-digit number.
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 1

36. Problem solving and reasoning questions
Complete each sentence. =
37 + = 47 =
+ 11 = 86
= 77
Add 11 to each number:
True or false?
Adding 11 to a 2-digit number with both digits the same (like 22 or 33) always gives another 2-digit number with both digits the same.
Adding 10 to a number where the first digit is 1 less than the second digit (like 12 or 23) always gives an answer with 2 digits the same.
Year 1

37. Problem solving and reasoning questions: Answers
Complete each sentence.
= 64
= 47
= 52
= 86
= 77 Some children may find the questions with the missing number on the left hand side (what has to be added to 37 to equal 47) trickier.
Add 11 to each number:
Mistakes may arise if children are counting on in 1s rather than adding 10 then 1 (‘Spider then fly’).
True or false?
Adding 11 to a 2-digit number with both digits the same (like 22 or 33) always gives another 2-digit number with both digits the same. False. It works for most, e.g = 33; = 44, but not for (=110).
Adding 10 to a number where the first digit is 1 less than the second digit (like 12 or 23) always gives an answer with 2 digits the same. True, e.g = 22; = 99.
Year 1