ABSTRACT
Suppose some instructional designers want to develop a learning environment to mediate subject matter knowledge about astronomy, especially about the development of stars. Should the designers use a text or a text enriched with graphics and pictures aiming at an illustration? Should they use a film aiming to make the topic more visible? Or should they illustrate the topic with a computer simulation aimed at interactivity? The designers know that the text allows readers to process at their own speed, or to regress and go back to review another part of the sentence they have just been reading. With films this is impossible. However, a film may be more vivid than a text. The designers do not know whether the retention for the material presented by films is as good as for information presented by texts or for information presented by texts augmented by pictures and graphics. They know, on the other hand, that many people report being able to remember a text they studied very intensively, whereas a film flies by quickly so that it may be difficult to remember details of content. Furthermore, a film cannot be presented in an interactive manner, however, this is possible with a computer simulation. Here, the learner can determine or choose several parameters and can control which effects the chosen parameters have on different processes. This example should demonstrate that instructional delivery and the related choice of a specific medium or media system may be a difficult task in the field of instructional design (ID).
