“课标”指出:“数学教学是数学活动的教学。教师要紧密联系学生的生活环境,从学生的经验和已有的知识出发,创设生动的数学情境……”“要重视从学生的生活实践经验和已有的知识中学习数学和理解数学。”所以,我们的教学要充分利用学生已有生活经验,从生活实际中引 “Class standard ” pointed out: “Mathematics teaching is the teaching of mathematics activities.Teachers should closely contact students’ living environment, starting from the student’s experience and existing knowledge, to create a vivid mathematical situation ... ” “ Emphasis is placed on learning mathematics and understanding mathematics from students ’practical experience and existing knowledge. ”Therefore, our teaching should make full use of the students’ existing life experience and from the actual life