lesson
Check with the opposite action
Read with an adult. You can say, point, draw or write your answer.
1 · Learn
Addition and subtraction undo each other. If 24 + 13 = 37, then 37 − 13 = 24. This can check an answer.
Swapping the parts in addition keeps the same total: 13 + 24 = 37. Subtraction does not work that way: 9 − 4 is not the same as 4 − 9.
2 · Worked example
To solve __ + 8 = 23, I calculate 23 − 8 = 15, then check 15 + 8 = 23.
3 · Your turn
Fill the gap: 46 − __ = 30. Check your answer using addition.
Check your answer
16. The check is 30 + 16 = 46.
4 · Apply your learning
Make a fact family from 12, 15 and 27, including two additions and two subtractions.
Adult guidance and safety
Use practical objects before symbols. Read the task aloud when needed and ask the child to explain, not just name an answer. Revisit with different examples; one successful answer is not proof of fluency.
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