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小数的大小比较的教学今天教学小数的大小比较。我想从整数和小高位数的大小比较的相同和不同点入手教学，就没有选用教材上的例题。
简单的复习以后，直接说明今天教学“小数的大小比较”，随手在黑板上板书：10000（）9999，学生答填“>”，我故作奇怪问：10000全是0和1组成的，9999可都是9组成的，9比0和1大多了。学生回答：因为10000的位数多。我板书①比位数，位数多得这个数就大。
接着又写了一个，6754（）6784，学生回答“<”，我问为什么？你先比的是什么？学生王妍说先从个位比，我立即举例：6781（）5699,5699的个位比6781大，能说5699比6781大吗？学生说不能，应该从高位比起。后接着又板书，位数相同，从高位比起，哪一位大这个数就大。
接着问：猜猜看，小数的大小比较和整数相同吗？
学生议论后教师逐条验证。
45.67（）45.9。学生说45.67>45.9，用钱解释：45元6角7分笔45元9角大。问45.67是几位小数？（二位），45.9是几位小数？（一位）。所以整数大小比较的第一条对于小数是不对的。
接着举例：5.678和5.679。先比那一部分？整数部分相同接着如何比。得出：先比整数部分，整数部分相同就再比十分位，十分位大的就大，十分位相同就再比百分位，……
我感到这样和整数连接，从旧知的引入比较自然，也便于总结出结论性的东西。
在接着提问的环节中，穆小云，一个数学学困生提出，如果一个数的后面没有数了怎么办？我立即举例4.567和4.56，大部分学生知道在后面补0接着比。大看出这个问题其它数学较弱的同学听后还是有启发的。
沈东波 发表于：2011-9-26 20:09:07
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码确 发表于：2018-9-5 20:11:30
