Module 4 Calculating
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Can I write addition and subtraction sentences that use the same three numbers and explain how they are linked?

Example review questions

  • Say two addition and two subtraction sentences to link the numbers 3, 5 and 8.
    Two hands showing 5 and 3 fingers
  • Complete these number sentences;
    5 + empty box = 9; empty box + 4 = 9; 9 – empty box = 5; 9 – empty box = 4
    What do you notice?
  • Draw jumps on a number line to show 9 − 3, 6 + 3, 3 + 6 and 9 − 6.
  • Write two addition and two subtraction number sentences to link 10, 4 and 14.
    Three place value cards marked 10, 4 and 14
  • What addition and subtraction sentences can you write for this number line?
    A number line showing 2 and 9
  • Use 1, 4, 5 and + , − , = . How many different calculations can you write?

Teaching guidance

This teaching guidance document suggests some of the key vocabulary, models, images and practical equipment that children should experience and be able to use. It also includes some teaching tips to provide a few starting points for ways of supporting children with this area of mathematics.

PDF file Can I write addition and subtraction sentences that use the same three numbers and explain how they are linked? - teaching guidance | 45KB new window

Consolidation and practice

These resources are to support children in guided or independent work.

XLS file Addition and subtraction number sentences spreadsheet | 96KB new window

PDF file Fact families activity | 20KB new window

Supporting children with gaps in their mathematical understanding

PDF file Is insecure in making links between addition and subtraction and/or recognising inverses | 71KB new window

PDF file Resource booklet | 501KB new window

Opportunities to use and apply

Possible contexts include:

  • Solving problems involving inverses, e.g. I think of a number, I subtract 9 and the answer is 20. What is my number? How did you work it out?
  • Using inverses when calculating, e.g. what addition facts could you use to help you calculate these? 10 − 6, 20 − 8
  • Checking, e.g. 14 + empty box = 25. What is the missing number? How do you know? What subtraction could you do to find the missing number?
  • Reasoning, e.g. if you give me any addition number sentence I can write one more addition sentence and two subtraction sentences using the same numbers. Is it sometimes, always or never true?
  • Word problems, e.g. eighteen children are on a bus. At the bus stop, five children get off and five children get on. How many children are on the bus now? How do you know?

Confirming learning

Ask probing questions such as:

  • Catherine said that 32 − 27 = 6. Is she correct? Which addition calculation could she use to check her answer?
  • Annie's teacher asked her to write two addition and two subtraction number sentences to link the numbers
    3, 5 and 8.
    She wrote these: 3 + 5 = 8, 5 + 3 = 8, 5 − 3 = 8, 3 − 5 = 8
    Are they correct? Explain your thinking.
  • Only one of these subtractions is correct. Which one is it? Explain how you know using the link between addition and subtraction.
    30 − 7 = 25, 28 − 5 = 18, 25 − 6 = 19, 14 − 4 = 12
  • Ling wants to check her answer to this subtraction:
    73 − 45 = 28
    Which of these tells Ling that her answer is correct?
    A. 73 + 45 = 118, B. 45 + 28 = 73, C. 28 + 73 = 91