我们在教学过程中,往往会遇到些平时常见、又不易为人们所重视的算理问题。因此,教师在教学时,应该以浅显问题为例,逐步解剖,向原理引伸,使学生知其然,也知其所以然。这样,无论是减轻学生的思维负担,还是开拓学生的思路,提高计算能力,都是大有益处的。下面,我就分数四则计算中常见的几个问题,作些简要的算理分析。(一)异分母分数加减法为什么要通分?我们在名数加减法里,单位相同的可以直接相加减;单位不同的,要先换算成相同单位后再相加减。比如,1米加5分米或1米减5分米。计算时应把米 In our teaching process, we often encounter some common problems that are not always easy to be valued by people. Therefore, when teachers are teaching, they should take the superficial issue as an example. They should gradually dissect and extend the principle so that the students know what they are and know why they are. In this way, both to reduce the burden of thinking students, or to develop students ideas, improve computing power, are of great benefit. Below, I will score a few of the four common problems, make some brief analysis of the arithmetic. (A) different denominator fractional addition and subtraction method why points? We add and subtract the name of the number, the same units can be directly added and subtracted; units are different, you must first converted into the same unit and then add and subtract. For example, 1 meter plus 5 meters or 1 meter minus 5 meters. Calculate the meter should be