同许多现象一样，学生的学业成绩在总体上也服从于正态分布：无论是很好的还是很差的都只是少数，更大量的则是处于一种中间状态。前者往往受到更多的关注，叫做“优生”；后者往往落入寂寞一隅，是为“差生”。如何采取有效的方法以提高差生的学习业绩，是摆在班主任面前的一 Like many phenomena, students’ academic performance is generally subject to a normal distribution: whether it is good or bad, it is only a minority, and a greater number is in an intermediate state. The former tends to receive more attention, called “yousheng”; the latter tends to fall into a lonely moment, it is “bad students”. How to take effective measures to improve the learning performance of poor students is a task that is placed in front of the class teacher.