In this article, I comment on the seven articles that appeared in the special issues of Educational Technology Research and Development (1998, 46(4); 1999, 47(2)
IMPORTANCE OF EDUCATIONAL TECHNOLOGY RESEARCH AND DEVELOPMENT[] There was a time when educational technology research was on the periphery of the more general body of research in education. Educational technology research was conducted by a relatively small, close-knit group of scholars who were focused on a fairly narrow range of issues, such as sequencing of instruction, learner control, and feedback. The design of instructional systems was the major focus of this community; media and technology were not (Clark, 1983). At the same time, educational technology development was shaped by narrow client concerns and driven by esoteric design models (Reigeluth, 1983). The narrowness of this focus minimized the impact that educational technology research had on the larger education research and practice communities. Educational technology research and development (R&D) is no longer on the margin or in the backwater of educational research. The Educational Technology Research and Development (ETR&D) special issues demonstrate that this research is now at the center of some of the most creative, original, and powerful work in education today. The projects described here and elsewhere (Jacobson & Kozma, in press) are not minor interventions of a mere 30 minutes or even an hour, as in past instructional technology (IT) studies (Clark, 1989). They are major projects--significant in both complexity and scope--that tackle some of the most challenging problems and explore some of the most important theoretical issues in education today.Among the difficult educational problems that these projects address is the learning of challenging topics in mathematics and science. The curricular loci of the projects include alge-