Many learners, perhaps most, can and frequently do supply useful representations and operations for themselves from the information externally available, regardless of medium used. On the other hand, learners will benefit most from the use of a particular medium with certain capabilities (as compared to the use of a medium without these), if the capabilities are employed by the instructional method to provide certain representations or perform or model certain cognitive operations that are salient to the task and situation, and which the learners can not or do not perform or provide for themselves. These representations and operations, in turn, influence problem solving and the ability to generate and use representations in subsequently encountered situations. This view of learning with media as a continuous, reciprocal interaction between person and situation--between learner and mediated information--is compatible with evolving aptitude-treatment interaction theory (Snow, 1989).