After pre-service teachers become teachers, traditional patterns of classroom discourse which they had experienced as students affect their classroom discourse implicitly. For this reason, it is needed to get a new insight for evaluating and reflecting a teacher`s classroom discourse. In this study, I analyzed the information flow of science classes of pre-service elementary school teachers. The finding showed that teachers` organizational skills for students` information made advanced science classes by maintaining discourse cohesions. And the findings also showed a way how to analyze, evaluate or reflect science classroom discourse. This trial could contribute to find out the characteristics of teachers` science classroom discourse and show the directions to them how to change their classes beyond impressionable evaluations for their science classes.