Introduction
At a recent educational-research conference, researchers were debating various approaches for using computer
networks in education. One group of researchers talked excitedly about new ways of delivering instruction to
students. They explained how lectures by expert scientists could be beamed down to thousands of schools. They
imagined the day when personal workstations will present problems to students, monitor student progress on the
problems, and automatically download video segments from network servers at appropriate times during the
instruction.