“凡事预则立,不预则废”。课堂教学是教学工作的主要形式,是一种有目的、有意识的教育活动,预设是课堂教学的基本特征,也是保证教学质量的基本要求。《全日制义务教育数学课程标准》指出:“数学教学不仅教给学生知识,而且要揭示获取知识的思维过程,而后者尤为重要。”教师如何去预设展示数学知识形成的过程,让学生参与数学知识的发现和探索,已成为每位数学教师必须思考的首要问题。 “Forewarned is forearmed, without prejudging the waste”. Classroom teaching is the main form of teaching work. It is a purposeful and conscious educational activity. The presupposition is the basic characteristic of classroom teaching and also the basic requirement of guaranteeing teaching quality. The full-time compulsory education mathematics curriculum standard states: “Mathematics teaching not only teaches students knowledge, but also reveals the process of acquiring knowledge, which is especially important.” "How can teachers pre-demonstrate the process of forming mathematical knowledge so that Students’ participation in the discovery and exploration of mathematical knowledge has become the primary issue that every teacher of mathematics must think.