等比数列前n项和公式推导的思维方法的产生是一个教学难点,如何突破这一难点?在新课改理念指引下,笔者试将这一问题交给学生讨论,取得了较好的效果,下面是其中的教学片断.教师:同学们都求过哪些数列的前n项和?学生1 :等差数列前n项的和.学生2 :形如1 ,-1 ,1 ,-1 ,1 ,…和2 ,2 , It is a difficult teaching point to draw the thinking method of the first n equal number formulas and formula derivation. How to break through this difficulty? Under the guidance of the new curriculum reform concept, the author tried to give this question to the students to discuss, and achieved better results. The following is a section of the teaching. Teacher: The students who have asked which series of the first n and ? Student 1: The sum of the n items before the arithmetic progression. Student 2: Form 1 ,-1,1,-1, 1 ,...and 2,2 ,