This experimental study was designed to determine the differences, if any, in achievement of fourth grade students taught by two different approaches to planetarium instruction. Nine randomly chosen sections of fourth grade students received planetarium teaching described as indirect. This teaching method included teacher lecture, discussion, teacher questions, student responses, and teacher praise for student responses. Nine other randomly chosen sections of fourth grade students received planetarium teaching described as direct. This teaching method included only teacher lecture. Students were discouraged from making any verbal responses. Audio-tape recordings were made of all the planetarium lessons and were later analyzed by the Flanders Interaction System in order to determine the degree of indirect and direct teaching which had occurred. The purpose of the interaction analysis was to verify that indirect and direct teaching had been accomplished. A non-equivalent control group design with a pretest and post test was used in which the treatment was randomly assigned to the preassembled classes. .... Under the limitations and conditions of this study there was no difference in achievement between the groups taught by the indirect and direct approach.