is currently Chair of the Learning Sciences program at the University of Wisconsin-Madison, and a founding officer of the International Society of the Learning Sciences (ISLS). Dr. Nathan studies the cognitive, embodied, and social processes involved in learning and teaching mathematics, science and engineering in classrooms and the laboratory, using analysis of discourse, survey and assessment instruments, and experimental design. Dr. Nathan examines teacher beliefs about student learning and the influences of the expert blind spot, where high content knowledge in teachers shapes their expectations of novices' conceptual development. Dr. Nathan also examines students' inventions of mathematical representations and strategies for reasoning about quantity and pattern. In the social setting of the classroom, Dr. Nathan explores the nature of collaborative discourse, gesture and action, and representations during learning and instruction. Dr. Nathan has secured over $12M in external research funds and has over 80 peer reviewed publications in educational research and cognitive science, as well as over 100 scholarly presentations to US and international audiences.