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在教学“能被3整除的数”一节时,九年义务教育六年制小学教科书第十册上的传统教法是这样的:①先求3的倍数,得出这样一列数…18,21,24,…,90,93,96,…,120,123,126,…②从个位上看,能看出这些倍数有什么特征吗?不能。说明判断一个数能否被3整除,不能用看个位的方法。③引导学生将这些倍数各位上的数加起来,看它们的和有什么特征?这些倍数各位上数的和都是3的倍数(1+8=9,9+3=12,1+3+8=12…)。最后得出规律:一个数各位上的数的和能被3整除,这个数就能被3整除。虽
In the teaching of “can be divisible by 3” section, nine years of compulsory education six years of primary school textbooks on the tenth of the traditional teaching method is this: ① first seek a multiple of 3, come to such a number ... 18, 21,24, ..., 90,93,96, ..., 120,123,126, ... ② From the first place, what are the characteristics of these multiples? Description to determine whether a number can be divisible by 3, can not use a bit of a method. ③ guide students to multiply the number of these multiples of you to see what their sum and the characteristics of these multiples of the sum of the number of youngest is a multiple of 3 (1 +8 = 9,9 +3 = 12,1 +3 + 8 = 12 ...). Finally come to the law: a number of the number of each and can be divided by 3, this number can be divided by 3. although