Contents: Preface. Part I: Coordinating Representations. K. Stenning, J.G. Greeno, R. Hall, M. Sommerfeld, M. Wiebe, Coordinating Mathematical With Biological Multiplication: Conceptual Learning as the Development of Heterogeneous Reasoning Systems. J. Vince, A. Tiberghien, Modeling in Teaching and Learning Elementary Physics. J.R. Frederiksen, B.Y. White, Conceptualizing and Constructing Linked Models: Creating Coherence in Complex Knowledge Systems. Part II: Provoking More Effective Modeling. R. Luckin, B. du Boulay, Construction and Abstraction: Contrasting Methods of Supporting Model Building in Learning Science. Z. Fund, Cognitive Support in Computerized Science Problem Solving: Eliciting External Representation and Improving Search Strategies. A. Bouwer, V.B. Machado, B. Bredeweg, Interactive Model-Building Environments. S. Bull, V. Dimitrova, P. Brna, Enhancing Reflective Modeling Through Communicative Interaction in Learning Environments. Part III: Collaboration and Language. P. Brna, M. Burton, Modeling the Modelers: Communicating About Content Through Shared External Representations. K. Lund, Teachers' Explanations of Students' Collaborative Modeling Activities. D. Alamargot, J. Andriessen, The "Power" of Text Production Activity in Collaborative Modeling: Nine Recommendations to Make a Computer-Supported Situation Work. M. Baker, Argumentative Interactions, Discursive Operations, and Learning to Model in Science.