A study was conducted to examine the effect of factors related to the format, presentation style, and order in which ideas are presented on students' recall of chemistry material. Data were obtained from students who viewed three different multi-image presentations in a large lecture hall setting. Following the presentations, students were required to submit a written summary of the material. As the student summaries were analyzed, bits of information reported were tallied on a master sheet listing ideas presented within each half-minute segment of the presentation. Study findings included the following: (1) impact appeared to be greatest during the first 5-minute portion of the presentation, with impact sufficient to cause students to report about 35% of all ideas presented; (2) impact declined, but was relatively constant for the next two 5-minute portions, and dropped to the lowest level during the 15- to 20-minute interval; (3) enumerated items shown with numbers and print on the screen to accompany photographs had heightened impact; (4) enumerated items listed first had greater impact than those listed later; (5) when pairs of parallel ideas were presented, the first one presented was likely to have greater impact than the second; (6) presenting a fixed number of ideas in a shortened time span did not necessarily decrease the impact or retention, unless the material was too compressed for comprehension; and (7) presentations with more than about 40 ideas or bits of information were likely to be less efficient, with impact dropping off as the information load increases. (AYC)