心算加法和减法（7岁以上）
Mental addition and subtraction (age 7+)
心算三位数与一位数的加法和减法
Mentally add and subtract a three-digit number and ones
学习证据 / Evidence
- 心算 345 + 7
- 心算 462 − 5
- 解释只有个位会改变（除非需要跨越整十）
- Calculate 345 + 7 mentally
- Calculate 462 − 5 mentally
- Explain that only the ones digit changes (unless bridging through a ten)
评估问题 / Assessment
{{name}}能否心算出“436 + 7”或“521 − 8”？也就是在保持百位和十位不变的情况下，只调整个位？
Can {{name}} work out '436 + 7' or '521 − 8' in their head — keeping the hundreds and tens unchanged while adjusting just the ones?