方差的概念是“统计初步”一章的教学难点之一 .究其原因 ,从知识体系和学生认知基础来分析 ,有三个方面 :( 1)方差是衡量一组数据波动大小的特征数 ,与平均数不同 ,学生几乎没有相关的认知基础 ,他们难以理解数据的“波动” ,对引入方差的必要性不理解、不认可 ;( 2 )方差的定 The concept of variance is one of the teaching difficulties in the chapter “Introduction to Statistics”. The reason, from the perspective of the knowledge system and students’ cognition, has three aspects: (1) Variance is a feature number that measures the size of a set of data fluctuations. Unlike the average, students have almost no relevant cognitive basis. They have difficulty understanding the “fluctuations” of the data. They do not understand or recognize the necessity of introducing variance; (2) The determination of variance