A critical problem in education is the lack of evidence available to serve as a guide for educators, educational product developers, and media researchers in selecting or designing visual illustrations which will be most effective in facilitating student achievement of specific educational objectives. This book summarizes studies evaluating the effectiveness of different types of visual illustrations presented in slides, television, programed instruction booklets, and textbooks, and the results of studies investigating the relative effectiveness of the different methods. A summary of results section discusses specific conclusions, including that the effectiveness of visualized instruction is primarily dependent upon the type of visualization used, the method by which the visualized instruction is presented, the type of educational objectives specified, student characteristics, and the technique used to focus attention on the essential learning cues in the visualized materials. Finally, a model for the emipirical validation of visual materials is presented. (SH)