教材分析本课有两个活动:第一,组装用动力拉动的小车。在重力小车装置中,铁垫圈有重量,绳子对小车可以产生一个水平方向的拉力。改变铁垫圈的数量,就改变了重力的大小,也就改变了小车拉力的大小。第二,研究拉力大小与小车运动的关系。五年级的学生对运动和力其实并不陌生,他们对物体受到力的 Textbook analysis There are two activities this lesson: First, the assembly of power-driven car. In the gravity trolley device, the iron washer has a weight, and the rope can generate a horizontal pulling force to the trolley. Change the number of iron washers, it changed the size of gravity, also changed the size of the car pull. Second, the study of the relationship between the size of the pull and the car movement. Fifth-graders are not strangers to exercise and power, and they are subject to physical exertion