【案例】课题:圆的周长。教学伊始,我创设了这样一个情境:装修工人要给一个圆形水池围一圈栏杆,你认为要做好这件事需要解决什么问题?学生回答:“需要先知道圆形栏杆的长度。”我再引思:“小精灵”和“芭比娃娃”比赛跑步,他俩以同样的速度同时从A点起跑,“小精灵”围绕外圆跑 【Case】 Subject: Round circumference. At the beginning of teaching, I created a situation where the decoration worker should give a circle around the circular pool. Do you think what problems need to be solved in order to do this? The student replied: “You need to know the length of the circular railings first.” Let me again think: “Elves” and “Barbie” race running, they both at the same time starting from the A point, “Elves” around the outer run