An experimental Interactive Video Disc (IVD) assessment program, funded partially by the National Science Foundation, was developed to assess science teachers' knowledge of safe management of lab facilities and activities. The IVD program contains two phases: (1) panoramic view of the lab room, including safety equipment and storage of chemicals; and (2) simulation of a typical lab general science activity, performed by four middle school students. Examinees, consisting of beginning and experienced science teachers, were asked to identify and verbally respond to a variety of safety events which were simulated in the IVD program. Examiners' verbal responses along with the video contexts in which they occurred, were recorded by the IVD system and transferred to conventional video tapes which were later used for scoring. Reliability of scores for the four different categories of safety (physical facilities, Chemicals, Lab techniques, and students' behavior) examined by calculating the mean correlation coefficients among three scorers, was found to be moderate to high. Evidence for content and construct validity were studied through job relatedness analysis, safety expert judgment and known group performance comparisons. Videodisk images of the panoramic and laboratory stages and safety simulator scoring sheets are included. Contains 19 references. (Author/MDH)