【案例描述】这是四年级的一节数学课,课题是《交换律》。首先通过计算得出2+3=3+2,3+4=4+3以后,学生都觉得“使两个加数交换位置,仍然会得到相同的和”。老师写下一句话“使两个加数交换位置之后,仍然能得到相同的和。”在黑板上面。1.师:这个结论只是根据两个特殊的例子巧妙地得出的,这样好像不够谨慎。然而我们可以把这个结论进行猜想(教师写一个问号在结论末尾)。 【Case Description】 This is a fourth grade math class, subject is “exchange law.” After calculating 2 + 3 = 3 + 2, 3 + 4 = 4 + 3 first, students all think “to make two exponentials exchange positions and still get the same sum.” The teacher wrote the sentence “After getting the two plus places, you still get the same sum.” 1 division: This conclusion is based on two special examples cleverly drawn, it seems not careful enough. However, we can guess this conclusion (the teacher writes a question mark at the end of the conclusion).