Science students often bring naive models of the natural world to the classroom which can be resistant to traditional methods of teaching. If both the teacher and the student are unable to detect and change these conceptions, the student's ability to learn may be seriously impeded. A solution to this instructional dilemma would be to devise a method which a teacher could use to determine whether such naive models, or alternative conceptions, are held by a student and, if so, help the student to develop a plausible conception more in line with the current scientific viewpoint to replace each alternative conception. This is a report on the investigation of such a method: a microcomputer-based system for the diagnosis and remediation of three Aristotelian alternative conceptions of force and motion held by 8th-grade physical science students. The present investigation employed a microcomputer-displayed, graphics-based system to select students for possession of alternative conceptions and to posttest following remedial instruction. When alternative conceptions were detected, the system presented two simulations which were designed to facilitate the student's alteration of one or more of these naive conceptions. The instructional strategies incorporated into the computer simulations were consistent with a theory of instructionally-elicited conceptual change which: a) facilitated the student's recognition and discovery of a phenomenon which was anomalous to his or her conceptual framework and which epitomized the relevant scientific concept, and b) allowed the student to manipulate the objects and relationships of the phenomenon, experiencing the consequences of that action, so that the student would gradually adjust his or her conceptual categories until the phenomenon became anticipated. Students who had completed the study of force and motion (completed students) exhibited a very different pattern of non-scientific answers on the computer diagnostic test than did students currently studying that topic (in-process students). The completed students who were selected for possession of alternative conceptions were facilitated by the computer simulations in altering their naive conceptions to a significant degree. The computer posttest supplied evidence of the students' short-term conceptual change, and the Retention Test 1.5 months later supplied evidence of robustness of the change. / Ed. D.