课堂教学是一个渐进的、多层次和多角度的非线性序列,是师生及多种因素间动态的相互作用的推进过程。在这个过程中,除了“预设”和“预设生成”外,往往还会产生一些意料之外而又有意义的信息材料,即非预设性生成。教学中如果能及时捕捉并有效利用这些非预设性生成的资源,将使课 Classroom teaching is a progressive, multi-level and multi-angle non-linear sequence, which is the process of dynamic interaction between teachers and students and many kinds of factors. In this process, in addition to the “default” and “preset generation”, often there will be some unexpected and meaningful information material, that is, non-default generation. Teaching in the timely capture and effective use of these non-pre-generated resources will make the class