This volume in the NATO Special Programme on Advanced Educational Technology addresses fundamental principles in the design of a dialogue component in intelligent tutoring systems. The purpose of the book is to link fundamental issues of communication and interaction to the more restricted domain of instructional dialogue. The papers are grouped into parts on: theoretical issues in instructional dialogue; theory into practice - interaction in learning environments; natural dialogue and interaction theory; and feedback and control in human-machine communication. The book originates from a NATO Advanced Research Workshop held in Italy in 1992 and the authors are leading researchers in educational technology, dialogue research and user-interface design.

External representations (pictures, diagrams, graphs, concrete models) have always been valuable tools for the science teacher. The formation of personal, internal, representations - visualizations - from them plays a key role in all learning, especially in that of science. The use of personal computers and sophisticated software has expanded into the areas of simulation, virtual reality, and animation, and students now engage in the creation of models, a key aspect of scientific methodology. Several academic disciplines underlie these developments, yet act independently of each other, to the detriment of an attainment of what is possible. This book brings together the insights of practicing scientists, science education researchers, computer specialists, and cognitive scientists, to produce a coherent overview.

This book derives from a workshop entitled 'Natural Dialogue and Interactive Stu dent Modeling', held October 17-20, 1992 in the Villa Cipressi in Varenna (Italy). The theme of the workshop focused on how approaches to natural dialogue and conversation contributed to the development ofa sophisticated dialogue component in intelligent tutoring systems. Researchers from the fields of educational technol ogy, dialogue research and user interface design were all invited to the workshop in order to ensure a broad knowledge base for the discussion of the main topic of the workshop. The workshop included a variety of presentations, most of which are presented in this book, as well as active discussions of a number of issues related to the main topic, such as: the intrinsic value of a dialogue component in an intelligent tutoring system verbal expressions (e.g., natural language) as a successful modality in a learning setting the application of results from other types of dialogue, such as information or task dialogues, in models of instructional dialogue the role of a teacher as an intermediary who provides motivation and support in learning as opposed to the role of a teacher as someone who just presents information. In the introductory chapter we have tried to combine these issues and link them to the papers that are presented in this volume."

External representations (pictures, diagrams, graphs, concrete models) have always been valuable tools for the science teacher. This book brings together the insights of practicing scientists, science education researchers, computer specialists, and cognitive scientists, to produce a coherent overview. It links presentations about cognitive theory, its implications for science curriculum design, and for learning and teaching in classrooms and laboratories.