Two experiments which compare the effectiveness of the auditory and visual elements in instructional films in order to study their relative contributions to learning are described in this paper. Two films dealing with aerodynamics were used in one experiment, and one film dealing with desert survival was used in the other. Multiple choice item tests were constructed covering the information in each film. Some of the items were based on information contained in the visuals, others on the commentary, and a third group on information to be found in both the visual and audio channels. Some items were visual, and some verbal. The aerodynamics films were shown to 430 ROTC trainees divided at random into eight test groups. The experiments, concerned with the overall effectiveness of the audio and video elements, yielded the following main conclusions: (1) Significant learning accrues from the presentation of the film as a whole, and from the presentation of either the audio or video channel alone. 2. Neither channel is consistently better than the other. 3. Both channels together are consistently better than either one alone. 4. In general, hearing the sound track in the dark appears to be slightly superior to hearing it in the light. (GO)