表面上:三个人都答错了On the surface: three wrong answers
- 题目Question
- y = −2x² + 4x + 1
- 学生 ALearner A
- 不懂系数符号与开口方向Doesn't connect sign to opening
- 学生 BLearner B
- 概念懂,但调不出顶点公式Understands the idea; cannot recall the procedure
- 学生 CLearner C
- 只是在这一题漏看负号Simply missed the minus sign once
- 关键Key
- 先用一个小问题区分原因Use one small question to separate the causes