Expert systems are computer programs designed to model the problem-solving ability of human experts. They have experienced tremendous growth and popularity since their commercial introduction in the early 1980s. Expert systems are now used in areas such as business, medicine, science, engineering and manufacturing. Their applications to the field of education have also provided extensive opportunities. In this study the effectiveness of an expert system as an educational tool is demonstrated by considering a typical case where an expert system was successfully developed to aid the teaching of digital electronics. A brief description of expert systems is provided and the steps followed to develop the required system are outlined. The techniques described can easily be adapted to a variety of other similar applications.