“课标”(2011版)对第一学段的估算,要求学生“能结合具体情境,选择适当的单位进行简单估算,体会估算在生活中的作用”。但在实际教学中,教师虽然为学生创设了具体情境,但还常出现“可以精算,还有必要估算吗”这样尴尬的场面,这是为什么呢?我们不妨来做一番研究。一、课堂回放人教版二年级上册第31页“加减法估算”一课。 “Class standard ” (2011 version) of the first semester of the assessment, require students “can be combined with specific situations, select the appropriate unit for a simple estimate, experience estimating the role of life ”. However, in the actual teaching, although the teachers create specific situations for the students, they often appear “embarrassing scenes” such as “can you do the actuarial calculations, and it is necessary to estimate?” Why is this? We might as well do some research. First, the class replay PEP second grade on the first 31 pages “addition and subtraction estimation ” class.