Year 2 · Mathematics · Algebra
Addition and subtraction facts
Becoming fluent with addition and subtraction facts within 20, using fact families to find missing numbers and writing number sentences for everyday stories.
Awaiting educator review. This material was drafted by our content team with AI assistance and is waiting for review by a qualified educator. Please check it suits your child before using it. Created 10 October 2026.
Learning goals
Learners will
- Recall addition and subtraction facts within 20 using known strategies.
- Use the link between addition and subtraction to find missing numbers.
- Write a number sentence that matches a word story.
Success looks like
- I can use doubles and making ten to work out facts quickly.
- I can find a missing number in a number sentence like 7 + ? = 15.
- I can write a number sentence for a story.
The big idea
Fluent number facts free up a child's thinking for bigger problems. The goal is not just speed — it is having reliable strategies that quickly give the right answer.
Doubles and near doubles: if your child knows 7 + 7 = 14, then 7 + 8 is one more, which is 15. Double 8 is 16, so 8 + 9 is 17.
Make ten: for 9 + 8, move 1 from the 8 to the 9 to make 10. Then 10 + 7 = 17. Two egg cartons of ten show this beautifully.
Every addition fact has a turnaround: 6 + 9 = 15 and 9 + 6 = 15. And every addition fact gives two subtraction facts: 15 − 9 = 6 and 15 − 6 = 9. Together these four facts are a fact family.
Fact families help with missing numbers. For 7 + ? = 15, think 'What do I add to 7 to get 15?' or use subtraction: 15 − 7 = 8. Hide counters under a cup to make this concrete: show 7, say there are 15 altogether, and ask how many are hiding.
To write a number sentence for a story, decide whether things are being joined (+) or taken away or compared (−). 'There were 14 birds and 6 flew away' becomes 14 − 6 = 8.
Worked examples
Using a near double
What is 6 + 7?
- Think of a double you know: 6 + 6 = 12.
- 7 is one more than 6, so the answer is one more than 12.
- 12 + 1 = 13.
Answer: 6 + 7 = 13.
Finding a missing number
Mia had 12 stickers. She was given some more and now has 20. How many was she given?
- Write the number sentence: 12 + ? = 20.
- Use the fact family: 20 − 12 = ?
- Count on from 12 to 20: 13, 14, 15, 16, 17, 18, 19, 20. That is 8.
- Check: 12 + 8 = 20.
Answer: Mia was given 8 stickers.
Practice check
Have a go, then check your answers. Each answer comes with an explanation.
Answer guide for parents
What is the missing number? 7 + ? = 15
8 — 15 − 7 = 8, and 7 + 8 = 15.
What is 9 + 8?
17 — Make ten: move 1 from 8 to 9 to make 10, leaving 7. 10 + 7 = 17.
Which is the turnaround fact for 6 + 9 = 15?
9 + 6 = 15 — A turnaround swaps the order of the numbers being added: 9 + 6 = 15.
What is 16 − 7?
9 — Think addition: 7 + 9 = 16, so 16 − 7 = 9.
What is the missing number? 13 − ? = 5
8 — 5 + 8 = 13, so 13 − 8 = 5.
Leo had 11 marbles. His sister gave him some more and now he has 18. How many marbles did his sister give him?
7 — 11 + ? = 18. Count on from 11 to 18: that is 7. Check: 11 + 7 = 18.
There were 14 birds on a fence. 6 flew away. Which number sentence matches the story?
14 − 6 = 8 — Birds flew away, so we subtract: 14 − 6 = 8.
If 7 + 7 = 14, what is 7 + 8?
15 — 8 is one more than 7, so 7 + 8 is one more than 14, which is 15.
Watch out for
- Reading the = sign as 'the answer comes next'. Show sentences like 15 = 7 + 8 and 7 + 8 = 9 + 6 so the sign means 'is the same as'.
- Adding the two numbers seen in a missing-number problem (for 7 + ? = 15, answering 22). Model with counters under a cup.
- Thinking subtraction has a turnaround like addition (13 − 5 = 5 − 13). Use objects to show this does not work.
Tips for parents
- Practise a few facts each day for two or three minutes rather than long drills.
- Ask 'How did you work that out?' — explaining a strategy matters as much as the answer.
- Use card games: flip two cards and add, or flip one card and find what makes it up to 20.
Go further
- Make a fact family 'house' poster for each total from 11 to 20.
- Play 'Hidden counters': place 20 counters, hide some under a cup and ask how many are hidden.
- Write your own word stories for a fact such as 9 + 6 = 15 and act them out with toys.