论文部分内容阅读
一、省编小学数学第九册,有一道冰水互变习题:“水结成冰时,冰的体积比水增加了1/11,当冰化成水时,水的体积比冰减少了几分之几?”求解这道习题时,有的同学往往会这样认为:“水结成冰,体积增加了1/11,冰化成水时,冰的体积当然也应当减少1/11。”乍看起来,似乎很有道理。其实,这正说明他们在解答分数应用题时,不会正确辨认标准数。我们认为这是分数应用题教学中的一个重要问题,为此解析如下,仅供参考。 1.图示法:如图一所示,当水结成冰时,把水的体积作为标准数,设它
First, the provincial primary school mathematics ninth book, there is an ice-water interdecadal exercise: “water ice, the ice volume increased by 1/11 than the water, when the ice into water, the water volume is reduced by a few ice When solving this problem, some students tend to think so: ”water ice, the volume increased by 1/11, ice into water, of course, the volume of ice should be reduced by 1/11." At first glance It seems that makes sense. In fact, this shows that they do not correctly identify the standard number when they answer the question mark application. We think this is an important issue in the teaching of fractional application questions, so we will analyze it as follows for reference purposes only. 1 pictorial method: As shown in Figure 1, when the water is ice, the volume of water as a standard number, set it