一、以旧引新“以旧引新”是常用的教学方法。这种教学符合学生学习知识的心理活动规律,有利于调动学生学习的积极性。要运用“以旧引新”的教学方法,首先必须掌握新旧知识之间的联系。新旧知识的联系是多种多样的,在中学数学教学中,经常采用的联系方式有下列几类: 1.对比:按照某些本质特征对于两种不同的事物进行对比,往往能达到“以旧引新”的效果。在教法安排上一般是先复习旧知识,然后对比着学习新知识,并着重弄清它们的区别与联系,特别是“区别”一定要弄清,因为正是这种“区别”,才标志着所学的知识是“新”知识。例如通过复习全等三角形的判定定理来学习相似三角形的判定定理,可以看出定理的结构 First, the old introduction of new “old introduction of new” is a common teaching methods. This kind of teaching accords with the law of psychological activity of students' learning knowledge, which is helpful to motivate students to learn. In order to apply the teaching method of “using old and new”, we must first grasp the connection between old and new knowledge. The connection between old and new knowledge is varied. In the middle school mathematics teaching, the frequently used contact methods are as follows: 1. Contrast: comparing two different things according to certain essential features can often achieve “ Introduce new ”effect. Generally speaking, we should review the old knowledge first and then contrast the new knowledge and focus on the difference and connection between them. In particular, “difference” must be clarified because it is this “distinction” that marks The learned knowledge is “new” knowledge. For example, by reviewing the judgment theorem of congruent triangles to learn the judgment theorem of similar triangles, it can be seen that the structure of the theorem