在计算“异分母分数的加减法”中,使用了“公分母必须是最小公倍数”的技巧,使得在化简结果时,工作量得以减小,教学之初,我也采用了这种思路。但是,正当我为传授给学生好的技巧窃喜时,新的苦恼来了:无论我如何强调“公分母必须找最小公倍数”这种思路的好处,部分学生依旧还是不用,这是什么原因呢?有学生认为:找最小公倍数要么用列举法,要么用短除法,这就好比在计算“异分母分数的加减法”时多了一步,太麻烦,况且找最小公倍数无论是用列举法还是短除法都容易 In the calculation of “addition and subtraction of different denominators,” the technique of “the common denominator must be the least common multiple” is used so that the workload can be reduced when the result of the simplification is reduced. At the beginning of teaching, I also adopted This idea. However, just as I was tricked into teaching students good tips, new distress came: no matter how much I emphasize the benefits of the idea that “the common denominator must find the least common multiple”, some students still do not use it. What is it The reason? Some students think: to find the LCM or enumeration method, or with a short division method, which is like in the calculation of “addition and subtraction of different denominator fraction ” step by step, too much trouble, Moreover, find the least common multiple Use enumeration method or short division method are easy