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最近我们组织了一次课堂教学评比,教学内容是“平方根”(人教版七年级下册第六章第一节),其中“探究2~(1/2)有多大”的问题是重点内容,也是教学的一个难点,上课教师千篇一律地利用教材介绍的夹逼法进行探究,不可否认,利用2~(1/2)的一系列不足近似值和过剩近似值无限逼近2~(1/2),既落实估算的方法,又渗透了用有理数逐步逼近无理数的极限思想.那么除了这种方法外,还有没有其他的方法逼近2~(1/2)呢?现提供另外一些方法,与同行研讨.
Recently, we organized a class teaching evaluation, teaching content is “square root ” (PEP VII seventh chapter, the first section), which “to explore 2 ~ (1/2) how much ” problem Is a key content, but also a difficult teaching, class teachers to use the textbook introduction of the clip force method to explore, it is undeniable, the use of 2 ~ (1/2) of a series of inadequate approximation and the approximation of the infinite infinite 2 ~ (1 / 2), both to implement the method of estimation, but also infiltrate the limit idea of using rational numbers to gradually approach irrational numbers.So there is no other way to approach 2 ~ (1/2) besides this method? Other methods are provided, Discuss with peers.