《数学课程标准》指出:“数学教学活动必须建立在学生的认知发展水平和已有的知识经验基础之上。”教师要根据学生已有的知识水平和生活经验,创设富有挑战性的数学问题情境,设计有思考价值的问题,激发学生的思考动机,使学生能忘情地投入到学习活动中去,让学生跳起来就能摘到“果子”。课堂教学中,教师精心设计问题、创设问题情境,才有利于激发学生的认知冲突,才能把教师教的主观愿望转化为学生的 Mathematical Curriculum Standards states: “Mathematics teaching activities must be based on the students ’level of cognitive development and existing knowledge and experience.” “Teachers should create challenging situations based on the students’ existing knowledge and life experience Of the mathematical problem situations, the design of thinking problems, stimulate students’ thinking motivation, so that students can devote themselves to learning activities to go, so that students can jump to pick ”fruit". In classroom teaching, teachers carefully design problems and create problem situations, which are conducive to arouse the students’ cognitive conflicts, so as to turn the subjective desire of teachers into students