Mathematics
Addition & Subtraction
Conceptual
6–7 yrs
Inverse: addition undoes subtraction
逆运算：加法还原减法
Description
Recognise and use the inverse relationship between addition and subtraction to check calculations and solve missing-number problems
Mastery Evidence
- Check 15 + 7 = 22 by calculating 22 − 7 = 15
- Use the inverse to solve: □ + 9 = 14, so □ = 14 − 9 = 5
- Explain that addition and subtraction 'undo' each other
Assessment Prompt
If your child works out 13 + 5 = 18, can they immediately use that to say '18 − 5 = 13' — without having to work the subtraction out all over again?
