Add and subtract two-digit numbers: a week of ready-to-teach maths
Five days of lessons for Year 2 Number. Print this pack and the week is prepared: each day has a one-page plan and a student worksheet, plus cut-out mats, number lines and sentence strips, a mini-check and every answer.
Start here: five minutes to Monday
- Skim the week at a glance on the next page.
- Print the five days. Each day is two A4 sheets: a plan and a worksheet.
- Cut out the two card sheets once; the mats, number lines and strips are reused all week.
- Open the free interactive unit on your board. Every plan tells you which picture to show and when.
- Teach straight from the plan. Timings, talk prompts, misconceptions and answers are all on the one page.
No maths background needed
This pack is written for the busy generalist teacher. Each plan explains the idea in plain words, lists the misconceptions children bring, and gives model answers, so you can walk in and teach it. Year 2 does not stack numbers in columns yet; it builds a toolbox of strategies, and each plan names the one for the day.
One day, one lesson
The five lessons fill a week of maths, one lesson of about 50 minutes a day. Run them in order: each day stands on the one before. Every lesson can also split into a short warm-up and a main session if your timetable runs small blocks.
The week at a glance
One lesson a day for a week. Each day stands on the day before, so run them in order.
| Day | Lesson | Children learn and do | On screen |
|---|---|---|---|
| 1 | Part, part, whole | Join two parts, find a missing part, and write number sentences | Parts and the whole |
| 2 | Jump it on the line | Add two-digit numbers by bounding tens and bridging to a ten | The kangaroo line |
| 3 | Split into tens and ones | Add by splitting, then rename ten ones as a fresh ten | Split and stack |
| 4 | Lean on a round number | Add and subtract near-ten numbers by rounding and adjusting | The round-number trick |
| 5 | Choose your strategy | Subtract by counting up and turn word problems into number sentences | The run chase |
How the week builds
Day 1 sets up part-part-whole thinking and number sentences, so subtraction is seen from the start as the same triangle read backwards. Days 2 and 3 build two ways to add: jumping along a line, then splitting into tens and ones and renaming the spill. Day 4 leans on a round number to add and subtract near-ten numbers, and Day 5 subtracts by counting up and lets children choose a route. It builds on Add and Subtract Within 20 from Year 1 and on renaming, and it opens the way to equal groups and to modelling with money.
Materials for the week (one trip)
- From the classroom: scissors, pencils, this pack printed.
- From home or the craft box: a handful of counters, buttons, coins or dry pasta to stand for the parts.
- Cut out once, use all week: the part-part-whole mats, the number cards, the number lines and the sentence strips in this pack. No maths equipment to buy.
Dear families
This week in maths, Year 2 adds and subtracts two-digit numbers. We do not stack numbers in columns yet. Instead we learn to see the parts and the whole, jump along a number line, split numbers into tens and ones, lean on a round number, and count up to find a difference.
Try this at home
- Spot two numbers today: two prices, two footy scores. Add them, then ask how many more one is than the other.
- Turn a shopping moment into a number sentence: 45 cents and 30 cents, write ____ + ____ = ____.
- Play how many more: we are on 38 and we want 63, so how many more? Count up together.
- For a near-ten number like 29, hand over a round 30 and give one back.
My maths this week
Fill one row a day. Tick when you have written a sentence and found the answer.
| Day | My numbers today | I wrote a sentence | I found the answer | My strategy was ____ |
|---|---|---|---|---|
| Monday | □ | □ | ||
| Tuesday | □ | □ | ||
| Wednesday | □ | □ | ||
| Thursday | □ | □ | ||
| Friday | □ | □ |
Printed from the free seegongsik Add and Subtract Two-Digit Numbers teaching pack · seegongsik.com/au/y2/number/AC9M2N04/pack
Part, part, whole
Two parts join to make a whole, and the same three numbers make an adding sentence and a taking-away sentence. Today children write number sentences for stories and find a missing part. Materials come first: hands convince faster than symbols.
We are learning to
- join two parts to make a whole,
- find a missing part when we know the whole and one part,
- write a number sentence for a story.
Success criteria
- I can write a number sentence for a story.
- I can find a missing part.
You need
A handful of counters, buttons or dry pasta to stand for the parts. The part-part-whole mats and number cards (cut-out sheet 1), one set per pair. The worksheet, one per child.
Lesson flow (about 50 minutes)
| 10 min | Make the whole Children put two small piles together and say the whole, then take one pile away and say what is left. Ask: “Two parts, one whole. If this part is 6 and that part is 4, what is the whole?” |
| 30 min | One triangle, two sentences Pairs lay two number cards as the parts, add to find the whole, and write both an adding sentence and a taking-away sentence for their triangle. Then cover one part and work it out. Ask: “Cover a part. You know the whole and one part. How can you find the part that is hidden?” |
| 10 min | Story to sentence Read a short story; children write the matching number sentence, then answer it. Ask: “In this story, is the missing number a part, or the whole?” |
Two half-sessions instead? End Session A after the triangle sentences. Start Session B by rebuilding one triangle, then move on to the stories.
Watch for these ideas
- Adding the whole and a part instead of subtracting to find the missing part.
- Reading a two-digit number as two separate digits rather than one quantity.
- Believing subtraction is a brand-new operation, not the same triangle read backwards.
Answers
- Join the parts: 34 + 52 = 86; 26 + 43 = 69; 45 + 38 = 83.
- Missing part: 45 + 25 = 70, so the part is 25; 32 + 26 = 58, so the part is 32; 24 + 36 = 60, so the part is 36.
- Story to sentence: 23 + 14 = 37 runs (the whole is missing); 40 - 15 = 25 beads (a part is missing).
Part, part, whole
The whole is the two parts joined. Add the parts to find each whole, then write an adding sentence.
Join the parts
| Part | Part | Whole | Adding sentence |
|---|---|---|---|
| 34 | 52 | ____ + ____ = ____ | |
| 26 | 43 | ____ + ____ = ____ | |
| 45 | 38 | ____ + ____ = ____ |
Find the missing part
You know the whole and one part. Find the other part.
45 + ____ = 70. The missing part is ____.
____ + 26 = 58. The missing part is ____.
24 + ____ = 60. The missing part is ____.
Story to sentence
Write a number sentence for each story, then answer it.
Sam scored 23 runs, then 14 more. How many runs in all? ____ + ____ = ____
A jar had 40 beads. 15 were taken out. How many beads are left? ____ - ____ = ____
Jump it on the line
A kangaroo never counts by ones when a big bound will do. Today children add two-digit numbers on a number line: bound by tens, bridge to a friendly round ten, then hop the ones.
We are learning to
- jump forward by tens on a number line,
- bridge to the next round ten,
- add two two-digit numbers by jumping.
Success criteria
- I can add by jumping tens then ones.
- I can bridge to the next round ten.
You need
The number lines (cut-out sheet 2), one per pair. The worksheet, one per child. A board number line the class can jump along together.
Lesson flow (about 50 minutes)
| 10 min | Bound by tens From any start, the class jumps on ten and says the landing, again and again. Ask: “Start at 26. Bound on ten. Where do you land? And ten more?” |
| 30 min | Bridge, then hop Model 38 + 25: hop 2 to bridge to 40, bound 20 to 60, hop 3 to 63. Pairs solve more on their lines and write the landings. Ask: “You are at 38. What small hop brings you to a round ten?” |
| 10 min | Say the jumps Children read their landings aloud from start to finish, like a commentary. Ask: “Tell me your landings in order: 38, 40, 50, 60, and then?” |
Two half-sessions instead? End Session A after Bound by tens. Start Session B with the modelled 38 + 25.
Watch for these ideas
- Landing past the target because the last small hops were not counted.
- Counting the start number itself as the first jump.
- Hopping by ones the whole way: this child needs more time bounding tens, not a faster method.
Answers
- 38 + 25 = 63; 46 + 32 = 78; 57 + 26 = 83; 29 + 43 = 72.
- Jumps vary. A good route for 57 + 26: 57, 60 (bridge 3), 80 (bound 20), 83 (hop 3).
- A good route for 29 + 43: 29, 30 (bridge 1), 70 (bound 40), 72 (hop 2).
Jump it on the line
Bound by tens, bridge to a round ten, then hop the ones. Write your landings, then the total.
Warm up: bound by tens
Fill each landing as you jump on ten.
26, ____, ____, ____
47, ____, ____, ____
Bridge, then hop
| Sum | My landings (write each number you land on) | Total |
|---|---|---|
| 38 + 25 | ||
| 46 + 32 | ||
| 57 + 26 | ||
| 29 + 43 |
Draw one jump story
Choose one sum above. Draw its jumps on a line: big bounds for tens, small hops for ones.
Split into tens and ones
Too big to add whole? Split both numbers into tens and ones, add each pile, then rename ten ones as one fresh ten. The renaming from earlier in the strand now earns its keep.
We are learning to
- split a two-digit number into its tens and ones,
- add the tens with the tens and the ones with the ones,
- rename ten ones as one ten when the ones make ten or more.
Success criteria
- I can split both numbers and add the piles.
- I can rename ten ones as a ten.
You need
The number cards (cut-out sheet 1) and counters to bundle. The worksheet, one per child. A board to record the two piles.
Lesson flow (about 50 minutes)
| 10 min | Split it Children split numbers into tens and ones aloud and with counters. Ask: “38 splits into which two parts? And 25 splits into which two?” |
| 30 min | Add the piles, then rename Model 38 + 25: tens 30 and 20 make 50, ones 8 and 5 make 13, box ten ones into a ten, so 50 and 13 make 63. Pairs do more and record each pile. Ask: “The ones made 13. That is more than a hand holds. What do we box up?” |
| 10 min | Watch the spill Compare a sum that renames with one that does not. Ask: “Before you add, how can you tell whether the ones will spill over a ten?” |
Two half-sessions instead? End Session A after the first modelled sum. Start Session B with Watch the spill.
Watch for these ideas
- Gluing the piles together, writing 70 and 13 as 713.
- Forgetting to rename when the ones make ten or more.
- Splitting 38 as 3 and 8 instead of 30 and 8.
Answers
- Split: 38 = 30 + 8; 25 = 20 + 5; 47 = 40 + 7; 56 = 50 + 6.
- 38 + 25: tens 50, ones 13, total 63. 27 + 48: tens 60, ones 15, total 75. 34 + 58: tens 80, ones 12, total 92. 45 + 39: tens 70, ones 14, total 84.
- 43 + 25 = 68, no renaming (the ones make 8). 56 + 29 = 85, renamed (the ones make 15).
Split into tens and ones
Split each number, add the two piles, then rename if the ones make ten or more.
Split each number
38 = ____ + ____
25 = ____ + ____
47 = ____ + ____
56 = ____ + ____
Add the piles, then rename
| Sum | Tens and tens | Ones and ones | Total |
|---|---|---|---|
| 38 + 25 | |||
| 27 + 48 | |||
| 34 + 58 | |||
| 45 + 39 |
Does it need renaming?
43 + 25 = ____. Did the ones make ten or more? Yes / No.
56 + 29 = ____. Did the ones make ten or more? Yes / No.
Draw the ten you box up
For 27 + 48, the ones make 15. Draw the loose ones, then ring ten of them to make a new ten.
Lean on a round number
Nobody hands over 29 in coins; you give a round 30 and take one back. Numbers ending in 9 or 1 are begging for it. Today children round a near-ten number, add or take away the round ten, then settle up. The trick works for adding and for taking away.
We are learning to
- change a near-ten number into a round ten,
- add or subtract the round number, then adjust,
- keep a ledger of the change so the answer stays true.
Success criteria
- I can round a near-ten number and adjust.
- I can add and subtract near-ten numbers with a round number.
You need
The worksheet, one per child, and pencils. The number lines (cut-out sheet 2) help children show the round jump and the small adjustment.
Lesson flow (about 50 minutes)
| 10 min | Next-door tens Name the round ten each number lives next to, and how far away it is. Ask: “29 lives next door to which round ten? How far away is it?” |
| 30 min | Round, then settle up Model 38 + 29: add 30 to get 68, give one back for 67. Then 52 - 29: take 30 for 22, put one back for 23. Pairs do more, adding then subtracting. Ask: “We handed over one too many. To make it true, do we give one back or pay one more?” |
| 10 min | Which way does the one go? Sort a few sums by whether you give one back or put one back. Ask: “You changed 39 to 40. That is one too many. When adding, do you give one back or pay one more?” |
Two half-sessions instead? End Session A after the adding examples. Start Session B with the subtraction examples.
Watch for these ideas
- Rounding but forgetting to adjust at the end.
- Adjusting the wrong way: giving one back when they should pay one more.
- When subtracting, taking the extra one away again instead of putting it back.
Answers
- Adding: 38 + 29 = 67; 45 + 19 = 64; 56 + 39 = 95.
- Subtracting: 52 - 29 = 23; 63 - 19 = 44; 84 - 39 = 45.
- The ledger: when adding a rounded-up number, give one back (take one off). When taking away a rounded-up number, put one back (add one on).
Lean on a round number
Change the near-ten number to a round ten. Add or take away the round ten, then settle up.
Adding: round up, then give one back
You added one too many, so give one back (take one off).
38 + 29: 38 + ____ = ____, give 1 back = ____
45 + 19: 45 + ____ = ____, give 1 back = ____
56 + 39: 56 + ____ = ____, give 1 back = ____
Subtracting: round up, then put one back
You took away one too many, so put one back (add one on).
52 - 29: 52 - ____ = ____, put 1 back = ____
63 - 19: 63 - ____ = ____, put 1 back = ____
84 - 39: 84 - ____ = ____, put 1 back = ____
Show one on a line
Choose one sum above. Draw the big round jump, then the small step that settles the one.
Choose your strategy
When two numbers are close, counting up beats counting back. Today children subtract by chasing the gap, then choose the best route for word problems, writing each as a number sentence. Choosing the route is the real skill of the week.
We are learning to
- find a difference by counting up from the smaller number,
- bridge through the next ten while counting up,
- choose a strategy and write a number sentence for a word problem.
Success criteria
- I can subtract by counting up.
- I can choose a strategy that suits the numbers.
You need
The number lines and sentence strips (cut-out sheet 2). The worksheet, one per child. A board for the class count-up.
Lesson flow (about 50 minutes)
| 10 min | How many more? From a score to a target, the class counts up together. Ask: “We are on 58 and we want 80. How many more to get there?” |
| 30 min | Chase the gap, then choose Model 80 - 58: count up 2 to 60, then 20 more to 80, so 22. Then give a mix of word problems; children write the sentence and pick a route: chase, jump, split or round. Ask: “Are these two numbers close, or far apart? Which route will be quickest?” |
| 10 min | Write it as a sentence Children turn one story into a number sentence on a strip and answer it. Ask: “In this story, what is the whole, and what is the part we already know?” |
Two half-sessions instead? End Session A after the count-up practice. Start Session B with the word problems.
Watch for these ideas
- Counting back and losing track instead of counting up.
- Forgetting to add the two counts: to the next ten, then on to the target.
- Choosing a slow route for numbers that sit close together.
Answers
- Count up: 50 - 27 = 23; 62 - 45 = 17; 80 - 58 = 22; 74 - 26 = 48.
- Word problems: 53 - 28 = 25 books; 36 + 27 = 63 cards; 45 + 38 = 83 in all; 60 - 42 = 18 free.
- Counts for 74 - 26: 4 up to 30, then 44 up to 74, so 48.
Choose your strategy
Count up from the smaller number: first to the next ten, then on to the target. Add your two counts.
Count up to subtract
| Take away | Up to the next ten | Then up to the target | Difference |
|---|---|---|---|
| 50 - 27 | |||
| 62 - 45 | |||
| 80 - 58 | |||
| 74 - 26 |
Word problems
Write a number sentence, choose a strategy, and answer it.
A shelf had 53 books. 28 were borrowed. How many are left? ____ ____ ____ = ____
Ava had 36 cards. Ben gave her 27 more. How many now? ____ ____ ____ = ____
The canteen sold 45 pies and 38 sausage rolls. How many in all? ____ ____ ____ = ____
There are 60 seats. 42 are taken. How many are free? ____ ____ ____ = ____
Draw one chase
Choose one take-away above. Draw the count up on a line: a small hop to the next ten, then a bigger hop to the target.
Part-part-whole mats and number cards
Cut out the mats and the number cards. Put a number card in each part, then add to find the whole; or write the whole, cover a part, and work out the part that is hidden. One set per pair is plenty.
Part-part-whole mats
Number cards
Teacher note: these are the parts and wholes the class meets on screen in “Parts and the whole”, so the mat game and the picture match.
Number lines and sentence strips
Cut out the number lines for jumping and counting up (Days 2, 4 and 5). Cut out the sentence strips to build a number sentence for a story: write a number in each blank.
Number lines (0 to 100)
Number-sentence strips
Teacher note: the lines are the same rails as “The kangaroo line” and “The run chase” on screen, so the paper jumps and the picture match.
What we know: adding and subtracting
Work on your own. Show your thinking if you can.
- Leo had 24 stickers and got 19 more. Write a number sentence for how many he has now: ____ + ____ = ____
- Fill the missing part: 35 + ____ = 80.
- 42 + 35 = ____
- 58 + 26 = ____
- Use a round number: 47 + 29 = ____
- Use a round number: 64 - 19 = ____
- Count up to subtract: 70 - 46 = ____
- A bus had 55 people. 27 got off. Write a number sentence and answer it: ____ - ____ = ____
Answers and marking guide
Answers
- 24 + 19 = 43.
- 45 (because 35 + 45 = 80).
- 77.
- 84 (the ones make 14, so a ten is renamed).
- 76 (47 + 30 = 77, then give one back).
- 45 (64 - 20 = 44, then put one back).
- 24 (46 up to 50 is 4, then 20 more to 70).
- 55 - 27 = 28.
A quick three-level guide
| Idea | Working towards | At standard | Beyond |
|---|---|---|---|
| Part-part-whole (Q1, Q2) | writes a number sentence with support | writes a matching number sentence and finds a missing part (35 + 45 = 80) | writes the whole fact family for the numbers |
| Add two-digit numbers (Q3, Q4) | adds tens and ones with materials | adds two two-digit numbers, renaming when the ones make a ten (58 + 26 = 84) | adds mentally and explains the jump or the split |
| Round and adjust (Q5, Q6) | rounds a near-ten number to a ten | adds and subtracts near-ten numbers by rounding and adjusting (47 + 29 = 76; 64 - 19 = 45) | explains which way the adjustment goes and why |
| Subtract and choose (Q7, Q8) | counts up with a number line | subtracts by counting up and writes a sentence for a story (70 - 46 = 24; 55 - 27 = 28) | chooses the route that suits the numbers and says why |
Eight questions, four ideas. A child at standard answers most questions and can say which strategy suits the numbers.
Weekly class record
Jot a tick as you move around the room; the mini-check fills any gaps. A tick a day is plenty.
| Name | Part, part, whole | Jump on the line | Split and rename | Round and adjust | Count up to subtract |
|---|---|---|---|---|---|
The five columns are the five days: part-part-whole, jump on the line, split and rename, round and adjust, and count up to subtract.