自然第三册《水的压力和浮力》一课的重点是指导学生研究物体在水中的浮沉规律。在教学中，我注重指导学生自行探索规律，充分调动了学生的积极性，收到了良好的教学效果。1．观察我先用幻灯演示一艘巨大的轮船飘浮在海面上，然后将一颗细小的大头针抛入水中。在学生仔细观察后 The third volume of natural “water pressure and buoyancy,” a lesson focuses on guiding students to study the law of object floating in the water. In teaching, I focus on guiding students to explore their own laws, fully mobilize the enthusiasm of students, received a good teaching results. 1. Watch me first with a slide show a huge ship floating on the sea, and then throw a small pin into the water. After careful observation of students