数学教学的传统做法是“先讲后练”。先由教师讲解“清楚”,然后才让学生“依样画葫芦”。教师在没有讲“清”。之前,始终不敢放心让学生练。长期的教学实践证明,这种教法弊病不少:其一,教师讲解学生洗耳恭听、“吃现成饭”。如此下去,当学生自己遇到新问题时只能束手无策。其二,教师为了“讲深讲透”,势必要占用大量的时间,学生练习的时间太短促。这样,不利于学生对新知识的巩固和技能的提高。其三,差生往 The traditional practice of mathematics teaching is to “stress after training.” Teachers first explain “clear” before allowing students to “follow suit.” Teachers did not say “clear.” Before, always afraid to let students practice. Long-term teaching practice has proved that this method has many shortcomings: First, the teacher explained that students are listening and listening, “eating ready meals.” So go on, when the students themselves encountered new problems can do nothing. Second, in order to “speak more thoroughly”, teachers are bound to take up a lot of time and the time for student practice is too short. In this way, is not conducive to student consolidation of new knowledge and improve skills. Third, worse students