[案例描述]本节课的教学内容原本是《同分母分数大小的比较》,教师出示:比较37和76的大小。由于教室墙壁刚粉刷过,凑巧在黑板上写37处分母7的位置上残留了少许白色的涂料,使7乍一看成了数字8。教师正准备将涂料擦净时,一个学生激动地喊“:老师,我能比出38和76的大小!”其他几个 [Case Description] This lesson’s teaching content was originally “compared with the denominator fractional size”, the teacher showed: compare the size of 37 and 76. As the walls of the classroom were freshly painted, it was a coincidence that a small amount of white paint remained on the blackboard at the position of 37 denominators, making 7 a figure of eight at first glance. When the teacher is going to wipe the paint, a student exclaims excitedly: “Teacher, I can out the size of 38 and 76!” Several other