The purpose of this study is to investigate patterns of linguistic communication in learning and teaching science and to find out how the formation of each pattern was related with the classroom, particularly in Korean middle school context. For this, we observed science classes in three middle schools in Seoul and collected data during lessons through audiotape and videotape recording. From the analysis of the data in three cases, nine patterns of spoken or written communication in learning and teaching science were found, and the features of each pattern and the context were discussed in detail. These results provided us with rich information of linguistic communication dealing with scientific topics appearing in Korean school science classes. We argue that those patterns appear to implicitly reflect the unique contexts of science classes in Korea. "The optimization in teacher behaviour", which refers to the conceptualization of teachers' efforts to take advantage of the given classroom context, is suggested as one of the main causes that made each pattern occur. (Contains 9 figures, 2 tables, and 2 notes.)