论文部分内容阅读
1.教师先出示3、4、5、三个数,让学生分别组成能被2、5整除的三位数。(能被2整除的数有:354、534;能被5整除的数有:345、435) 2.试一试。请学生仍用这三个数尝试组成能被3整除的数,并试除检验。(由于受“能被2、5整除数的特征”思维定势的影响,学生容易从个位上的数是否是3的倍数去考虑,从而组成543、453) 3.设置“陷井”。在学生用543、453试除以3,发现能整除后,教师引导学生思考:能被3整除的数有什么特征?(学生可能通过上面的特例得出:个位数字是3的数能被3整除,个位数字是3、6、9的数能被3整除,从而假设出:个位上的数是3的倍数的数,能被3整除)
1. Teachers first show 3, 4, 5, three numbers, so that students can be composed of three divisible by 3, 5, respectively. (Divisible by 2 are: 354,534; divisible by 5 are: 345,435) 2. Give it a try. Ask students to still use these three numbers to try to make up the number that can be divisible by 3, and try the test. (Students are easily accounted for by multiplying the number of quartiles by a multiple of 3 to make up 543,453 due to the influence of “being able to be divisible by the divisor of 2,5”.) 3. Set up a “trap.” After the student divides by 543,453 and finds that divisibility can be found, the teacher guides the student to think: What is the characteristic of the number that can be divisible by 3? (The student may deduce from the above special case that the unit digit is the number of 3 3 Divide, the number is 3,6,9 can be divisible by 3, so as to assume that: the number of one-digit is a multiple of 3 can be divisible by 3)