Andrea A diSessa is Corey Professor Emeritus of Education at UC Berkeley. He has an AB from Princeton and a PhD in physics from MIT. He is a member of the National Academy of Education and a Fellow of the American Educational Research Association. Prof. diSessa joined Seymour Papert’s Logo group in 1972, and is well known for his early (1981) book on Turtle Geometry (with Hal Abelson) and for developing the Boxer computational medium, along with associated ideas about computational literacies. He has written over a hundred articles and chapters, and authored or edited a half dozen books and monographs, including Changing Minds: Computers, Learning, and Literacy (MIT Press). Recent work has tilted toward empirical and theoretical study of learning, particularly the role of intuitive knowledge in science learning, as founder of the “knowledge in pieces” approach to conceptual change. Current work includes teaching and studying the learning of dynamical systems theory (“patterns of change and control”) by pre-high school students, and writing a sequel to Turtle Geometry in physics.