加减法（9岁以上）
Adding and subtracting (age 9+)
解决情境中的多步骤加减法问题，判断每一步该用哪种运算和方法，并说明理由。
Solve addition and subtraction multi-step problems in contexts, deciding which operations and methods to use and why
学习证据 / Evidence
- 一所学校第一周收集了12,450个瓶子，第二周收集了8,372个；目标是25,000个——还差多少个？
- 每一步要在口算和笔算之间作出选择，并说明理由。
- 解决一道涉及五位数加减法的三步问题。
- A school collects 12,450 bottles in Week 1 and 8,372 in Week 2; their target is 25,000 — how many more do they need?
- Choose between mental and written methods for each step and explain why
- Solve a three-step problem involving addition and subtraction of five-digit numbers
评估问题 / Assessment
如果给{{name}}一个多步骤问题——比如制定预算，需要分几步计算收入和支出——能判断每一步该用哪种运算，并解释自己的思路吗？
If {{name}} is given a multi-step problem — like planning a budget where money is added and spent in several steps — can they decide which operations to use at each stage and explain their thinking?