《根对无机盐的吸收》一节是初中植物学第三章《根》的教学难点和重点。其内容偏重于理性知识,如果讲授太深,必然牵涉到许多化学知识,要使初一学生听懂,是有一定困难的。但照本宣科,则易于枯燥乏味,也不能调动学生的积极性。如果在忠实于教材的基础上,适当增加一些学生已知或易于接受的概念,运用启发式、直观性进行教学,这对于启发学生的思维、培养智能会有一定好处的。按教材要求做好演示实验,但必须选用幼苗。否则会因植物体内含有较多的无机盐而延长培养时间。通过学生对此实验的观察、比较,得出结论:土壤溶液中含有植物生长所需要的物质,使植物生长得健壮,而蒸馏水中不存在这些物质。此时,学生就会产生一个问题:这些物质是什么呢?如果你直接讲,这些物质就是无机盐,则缺乏启发性,学生也难于理解接受。如果补充一个实验:在土壤浸出液和蒸馏水中 The section “The Roots of Absorption of Inorganic Salts” is a difficult and focused teaching point in Chapter III “Roots” of junior high school biology. Its content is more emphasis on rational knowledge. If the teaching is too deep, it will inevitably involve many chemical knowledge. To make it easy for first-year students to understand it, there is some difficulty. However, according to this syllabus, it is easy to boring, can not mobilize the enthusiasm of students. If faithful to the textbook based on the appropriate increase of some students known or accepted concept, the use of heuristic, intuitive teaching, which is to enlighten students thinking, intelligence will have some benefits. According to the requirements of teaching materials demonstration experiments, but must use seedlings. Otherwise, the plant body will contain more inorganic salts to prolong the incubation time. Through the students’ observations and comparisons of this experiment, it was concluded that the soil solution contains the substances needed for the growth of the plants, so that the plants can grow robustly, but these substances do not exist in the distilled water. At this point, students will have a question: what are these substances? If you say directly that these substances are inorganic salts, the lack of enlightenment, students also difficult to understand acceptance. If you add an experiment: in soil leachate and distilled water