Empirical studies of medical technology students indicated that there is a considerable need for additional skill development in performing tasks such as antibody identification. The transfusion medicine tutor (TMT) explores the use of a model of expert problem-solving to direct the application of a variety of teaching strategies in such an environment. This tutoring system focuses on red cell antibody identification, which is a problem-solving task where multiple primitive solutions can be true simultaneously. The approach to tutoring is the design of a problem-solving environment in which the computer plays an active role in tutoring the student. TMT allows students to gain experience by exploring a wide range of patient cases. The design of TMT makes it easy for the computer to detect certain types of errors. TMT allows more advanced students to compare the conclusions they have drawn from a particular test result with the computer's interpretation of the same data.<<ETX>>