Commerce information high schools offer diverse computer related courses, and a number of different textbooks were published for each course. Since each corse covers broad area, the textbook has difficulties in keeping up with the rapid change. It is even more difficult to find textbooks that suit the needs and requirements of a school. Very frequently, chapters on application software cover software packages that are different from what school has in terms of producer or version. This kind of difficulties can be overcome by subdividing textbooks into lessons, and selecting lessons and textbooks for them that are most appropriate for each school. This paper proposes a way to subdivide computer textbooks into lessons, and discusses the advantages that come from it.