responsible for reviewing the English of the contributions. February 1992 Andree TIberghien Heinz Mandl Table of Contents Introduction 1 1. Teaching Situations and Physics Knowledge Introductory University Courses and Open Environment Approaches: The Computer as a Multi-role Mediator in Teaching/Learning Physics 5 E. Balzano, P. Guidoni, M. Moretti, E. Sassi, G. Sgueglia Practical Work Aid: Knowledge Representation in a Model Based AI System 21 J. Courtois Simultaneous Processing of Different Problem Aspects in Expert Problem Solving: An Analysis in the Domain of Physics on the Basis of Formal Theories of Commonsense Knowledge 35 A. Hron Modelis: An Artificial Intelligence System Which Models Thermodynamics Textbook Problems 47 G. Tisseau 2. Different Approaches to Student Modelling Steps Towards the Formalisation of a Psycho-logic of Motion 65 J. Bliss, J.