He has 16 years of experience in research and development related to intelligent tutoring systems and authoring tools for tutoring systems. He is one of the original developers of the Cognitive Tutor Geometry curriculum. He has conducted research in real educational settings, in urban and suburban schools at the high school, middle school, and vocational school levels, as well as at the postsecondary level. He is a member of the executive committee of the Pittsburgh Science of Learning Center ( http://www.learnlab.org).