一、研究背景新课改在初中科学教学中提出:教师要让学生在学习过程中去实现自主学习、合作学习和探究学习。即要重视学生的发现学习、探究学习、研究学习。从生产生活中挖掘教学资源,再经过自己的实验和观察建立起模型,来学习新的知识,才是最有效的教学过程。杠杆是生活中极为常见的一种机械,本节课无论是知识技能还是科学方法上都具有实际意义。二、学情分析八年级教材已经学习了力的作用效果和平衡知识,本节从新的角度,在不同层次上研究了这个问题,其内容是前面所学知识的扩展,也是后面滑轮、轮轴等其他一些简单机械的基础。通过本节课的教学,继续向学生渗透物理来源于生活,经过观察、实验等手段建构物理模型, First, the research background The new curriculum reform in science teaching in junior high school proposed: teachers should let students in the learning process to achieve autonomous learning, cooperative learning and inquiry learning. That is to pay attention to the discovery of students learning, inquiry learning, research and study. It is the most effective teaching process to tap the teaching resources from the production life and establish the model through our own experiment and observation to learn new knowledge. Leverage is a very common machine in life. This lesson is of practical significance both in terms of knowledge and skills and in scientific methods. Second, the academic analysis eighth grade teaching materials have been learning the effect of force and balance of knowledge, this section from a new perspective, at different levels to study this issue, its content is the expansion of the previous knowledge, but also behind the pulleys, axles, etc. Some other simple mechanical basis. Through the teaching of this lesson, continue to infiltrate students into physical life, through observation, experiment and other means to construct physical model,