“周长”这一内容属于空间与图形领域,也是学习图形面积、体积等的基点。然而纵观以往关于这一内容的教学,往往忽视了“人”这一因素,很多情况下,也许因为人员、时间、空间的限制,未能充分展开这一学习活动过程。过多的传授,学生只是单一的死记公式,未能很好地经历“周长”这一概念和计算方法的形成过程,少了那一份体验与感悟,学习的结果也总是不尽如人意。下面笔者以《周长公式的推导》教学为例,从两个教学片断对比分析中做一些深层次的思考,得出 “Perimeter ” This content belongs to the space and graphics areas, but also learning graphics area, volume, etc. of the starting point. However, in the past, teaching on this content often neglected the factor of “people”. In many cases, the process of learning may not be fully carried out due to the limitation of personnel, time and space. Too much teaching, students only a single death remember formula, failed to well experience the formation of the concept of “perimeter” and calculation methods, less that experience and insights, the results of learning are always not Enough. The following author to “Derivation of Perimeter formula” as an example, from the comparative analysis of two teaching fragments to do some deep thinking, drawn