一、教学生正确认识“已知”,和“未知”,“因为”和“所以”初学几何的学生,往往“已知”、“未知”,“因为”、“所以”搞不清楚,对它们之间的关系缺乏认识,靠想当然证题.尤其是证明一个命题形式的题,判断已知条件、求证、作图都得靠自己动脑,就感到更困难.这时,我先要求学生把一个命题写成“如果…,那么…”的形式,以便分清题设和结论,接着告诉他们题设就是“已知”, First, to teach students a correct understanding of “known” and “unknown”, “because” and “so” beginner geometry students, often “known”, “unknown”, “because”, “so” confused, right Lack of understanding of the relationship between them, of course, to prove the problem .Especially to prove a propositional form of the problem, to determine the known conditions, verification, mapping have to rely on their own brains, it is more difficult .At this time, I first ask students to A proposition is written in the form of “if ..., then ...” in order to clarify the hypothesis and conclusion, and then tell them that the inscription is “known”