In most existing computer assisted instruction (CAI), the nature of the instruction would not actually require a computer. Text is presented and read, questions are asked, and then materials are presented or reviewed depending on students' answers. There are two problems with this approach: computer capabilities for interactive task simulation are underused, and the tacit requirement to present instruction and tests in text form makes learning more difficult for many tasks. These problems may be the reason that little, if any, difference in effectiveness is found between computerized and non-computerized versions of instruction. Recent emphasis in research on mental representations in learning and on work/task simulations for instruction provides a basis for what may be a significant advance in techniques for CAI design. When these ideas are coupled with advances in computer science and technology that make it easier to develop interactive task representations, substantial gains in effectiveness are possible. This paper reviews the problems and selected research and theory, and presents several examples of recent work in CAI implementation that attempt to overcome the problems. Suggestions are derived from this work for the systematic development of design technology for interactive CAI. (Author/LMM)