“浮力”一章在整个中学阶段是一个独立单元,放在初中阶段学习。本章内容不多,但难点却不少,所以教好这一章内容无疑不是一件容易事。笔者到各农村中学收集了不少学生意见,他们普遍反映阿基米德定律好记,但真正运用到实际问题中去,却又无从下手。本章课后练习中有这样题目:有一方木块,当它浮在水上时,露出水面的部分大约是它总体积的五分之二,这块方木的密度是多少?把上题中的方木放在另一种液体中,它露出液面的部分大约减少到总体积的三分之一。这种液体的密度是多少?按课文要求,这两道题是要学生完成的练习,可是不少学生无从下笔,问题在哪里呢? 经过分析,我认为这是因为学生对阿基米德定律 The “buoyancy” chapter is an independent unit throughout the middle school period and is taught at the junior high school level. There are not many contents in this chapter, but there are many difficulties. Therefore, teaching this chapter is undoubtedly not an easy task. The author went to all the rural middle schools to collect a lot of student opinions. They generally reflect that Archimedes’ law is easy to remember, but they are actually applied to practical problems, but they have no way to start. In the exercises after this lesson in this chapter, there is such a problem: When there is a wooden block, when it floats on the water, the exposed part is about two-fifths of its total volume. What is the density of this square wood? The square wood is placed in another liquid and the portion of the liquid exposed to the liquid surface is reduced to approximately one-third of the total volume. What is the density of this liquid? According to the textual requirements, these two questions are exercises that students must complete. However, many students are unable to write. Where are the problems? After analysis, I think this is because of the students’ rule for Archimedes.