华罗庚教授在数学归纳法中强调:“要勇于退,足够地退,退到最原始而不失重要的地方,是学好数学的一个诀窍。”在数学学习中,学生的认知起点常常超越教材的逻辑起点,他们已有的认知经验、思维方式也时常出乎我们的意料。面对这样的情况,教师就必须善于退,主动地退,只有这样,学生才能更好地构 Professor Hua Luogeng emphasized in mathematics induction: “In order to dare to retreat, retreat enough, retreat to the most primitive and important place, is a knack for learning mathematics. ” In mathematics learning, the student’s cognitive starting point often Beyond the logic starting point of textbooks, their cognitive experience and way of thinking often go beyond our expectation. Faced with such a situation, teachers must be good at retreat, take the initiative to retreat, the only way for students to better structure