牵牛要牵鼻子,教学要抓关键,大家都懂得这个简单的道理。但是,在实际教学中,并非都能做得很好。许多老师证几何题,很快添上了辅助线,问题便“顺利”地解决了。有些老师讲因式分解题,用几种基本方法试验都不行,引导学生考虑拆项,但随即自己点出某一项,把它拆开后,分组进行分解,问题也“顺利”解决了。两课皆顺流直下,学生也并未提出任何问题。画辅助线,拆某一项,等等,这在解数学题中是极平常的动作,似乎非常简单。但为什么要添这条辅助线?你是怎样想起要添这条辅助线的?为什么添这条而不添别的?……这些都是学生在学习中隐含着的问题。教师避开(不论有意或无意)了这些问题,直截了当地添上辅助线,拆开某一项,问题似乎“迎刃而解”了,学生似乎都懂了,实际上, To bring the nose to pull the nose, teaching must grasp the key, we all know this simple truth. However, in actual teaching, not all can do well. Many teacher certificates geometric problems, quickly added auxiliary line, the problem will be “smooth” solution. Some teachers say that factorization problems, with several basic methods of testing will not work to guide students to consider demolition items, but then point out a certain one, put it apart, the group decomposition, the problem is also “smooth” solution . Both classes are downstairs, and the students did not raise any questions. Draw a line, demolition of a project, and so on, which is a very common action in solving mathematical problems, it seems very simple. But why add this guideline? How do you think of this guideline? Why do you add this article without ...? These are the problems that students implicate in their studies. Teachers avoid (whether intentional or unintentional) these problems, put bluntly the auxiliary line, disassemble a certain question, the question seems to be “solved”, the student seems to understand, in fact,