新课程理念认为:课堂教学是教师和学生共同的生命历程,课堂教学应当焕发生命的活力。它所提出的最高宗旨是“一切为了每一个学生的发展”。而“发展”却是一个生成性的动态过程,这个过程中的因素和情景我们往往无法预见。新课程理念指导下的生成性课堂具有不可预定性,其随机性造就了许许多多的生成性问题。可以说预设与生成作为一对矛盾统一体,共同存在于课堂教学之中,预设中有生成,生成离不开预设。只有预设的课堂也许是有秩序的课堂, The idea of ​​the new curriculum that: classroom teaching is a common life course of teachers and students, classroom teaching should be full of life vitality. Its supreme purpose is “everything for every student’s development.” And “development ” is a generative and dynamic process. The factors and situations in this process are often unpredictable. The generative classroom guided by the new curriculum concept has unpredictability, and its randomness has created a lot of generative problems. It can be said that presupposition and generation as a pair of contradictory unity, coexist in the classroom teaching, there are presuppositions generated, the formation can not be separated from the default. Only the default classroom may be an orderly classroom,