A black box is defined as a theoretical device with concealed inner mechanisms, where output can be obtained simply through input. While lay people utilize the black box when they confront given scientific knowledge, experts have a more complex grasp of it; their knowledge is a clear box. This paper examines how the black box is used in the learning process of people who fall between specialists and the general public by analyzing several textbooks for science students. We categorized the practiced methods into three models and expanded the science communication by envisaging concrete examples. The first model is a constructing-type; initially the author describes the inner mechanism, and then summarizes it as a black box. Second is a disclosure-type; he/she begins by introducing the knowledge as a black box and then gives a minute explanation of it. Third is an analogy-type; the author refers to existing knowledge and compares it to further knowledge without specific details. We suggest studying science communication from the viewpoint of these models.