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在讲“细胞的分裂”一节课时,教学活动一开始,我就向学生提出:一潭死水为什么会变绿发臭?一头小羊为什么能长成一头大羊?一只母鸡为什么能下许多蛋?蛋又为什么能孵化出小鸡?这些生物界中普遍存在的生命现象,引起了学生很大的兴趣,课堂上议论纷纷.当他们急于寻求答案的情绪表露出来的时候,我点出课题——细胞的分裂.然后用三张挂图,介绍细胞分裂的三种方式——无丝分裂、有丝分裂和减数分裂.通过三张挂图分析比较,得出细胞分裂的三种方式的概念及区别,再突出这节课的重点——有丝分裂.
In the course of teaching “Cell Division”, I began to ask students: Why can a dead water turn green and stink? Why can a lamb grow into a big sheep? Why can a hen lay many eggs? Why can eggs hatch chicks? The phenomenon of life that prevails in these biological worlds has aroused a great deal of interest among students. There have been many discussions in the classroom. When they are eager to seek answers, emotions are revealed. - The division of cells. Then three charts are used to introduce the three ways of cell division: amitosis, mitosis and meiosis. Through the analysis and comparison of three charts, the concepts and differences of the three ways of cell division are drawn. Highlight the focus of this lesson - mitosis.