“圆的周长”是六年制小学数学第十一册第四单元的教学内容。本节课是在学生掌握了最基本的直线图形———长方形和正方形周长的含义以及计算方法的基础上，安排的平面上最基本的曲线图形———圆的周长的教学。从直线图形到曲线图形，学生的学习在内容和研究方法上都有所变化 “Circumference of the Circle” is the teaching content of the fourth unit of the eleventh volume of the six-year elementary school mathematics. This lesson is based on the students grasp the most basic straight-line graphics --- the meaning of the rectangle and the perimeter of the square and the calculation method based on the arrangement of the plane's most basic curve graphics --- circle perimeter teaching. From straight-line graphics to curvilinear graphics, student learning has changed in both content and methodology