This paper describes the development of a case-based system for information technology (IT) education, to be used in high schools across Japan, so that teachers can share a common knowledge about IT education. The first section covers the study purpose and describes the case-based system, including registration of cases, searching cases, and adjusting search results. The use of case-based reasoning (CBR) theory in the construction of educational systems is described in the second section. The third section outlines the following components of the system architecture: use of the World Wide Web; the case base, including profile, contents, and address descriptors; the interface; case registration; and case search, including approximate cases and the similarity function. The final section explains the process of CBR learning in more detail, including case modification, case diagnosis, and case repair. Three tables present possible values for profile, contents, and address descriptors. (DLS)