【教学案例】一根细细的绳子,虽说不起眼,却在一节数学课上起了大作用。题目1:用一根长12.56分米的铁丝,围成一个正方形,面积是()平方分米;围成一个圆,面积是()平方分米。我发给每组一根绳子,然后让他们实际操作。“假如这根绳子长12.56分米”我的引导话语刚落,一个学生突然站起来说:“老师,我知道了,12.56分米是正方形的周长。”于是,在黑板上出现 Teaching case A thin rope, though modest, actually plays a big role in a math class. Question 1: With a length of 12.56 decimeter wire, surrounded by a square, the area is () dm; formed a circle, the area is () dm. I give each group a rope, and then let them practice. “If this rope is 12.56 meters long,” one of my guiding words had just fallen off and a student suddenly stood up and said, “Teacher, I know, 12.56 decimeter is the perimeter of the square.” "So on the blackboard appear