【背景分析】本教学案例是笔者的一节市级公开课,案例突出了用比值定义法构建速度概念的教学思想,简化了教学的难点.通过本节课的学习学生更容易理解速度的意义,并且也为以后学习密度、压强、功率等物理量打下了基础. 【Background】 This teaching case is a writer’s municipal open class, the case highlights the concept of ratio definition method to construct the concept of speed teaching, simplifying the teaching difficult.Through this lesson students are more likely to understand the meaning of speed , And also laid the foundation for future study of density, pressure, power and other physical quantities.