笔者曾听过一节讨论课 ,课题是“四种命题 (二 )” ,讨论的是原命题为真时 ,逆命题、否命题、逆否命题的真假 .学生都作了充分的准备 ,侃侃而谈 ,虽观点基本上都是课本列出的 ,但考虑问题角度有别 ,所举例子各不相同 ,气氛相当热烈 ,从调动学生主动性、从学生投入来说 ,效果非 The author once heard a discussion class. The topic is “Four Propositions (II)”. The discussion is about the original proposition, the converse, the proposition, the true or false of the negative proposition. The students are fully prepared. In an embarrassing conversation, though the viewpoints are basically listed in the textbooks, the perspectives of the problems are different, the examples are different, and the atmosphere is quite enthusiastic. From the perspective of mobilizing students’ initiative and student input, the effect is not.