A study analyzed the number and types of contributions that girls and boys made to a science discussion in a sixth-grade class. A 48-minute, student-centered cross-discussion was videotaped and analyzed. The exceptionally long discussion and the complexity of the topic (involving moving shadows and frames of reference) make the lesson a rich source of information. Results indicated that girls in the class contributed far less than would be equitable given their representation in the class's population, but that boys and girls spent roughly the same percentage of turns they did take in giving explanations. Far more of the girls' remaining turns, however, were concerned with such interactional issues as allocating turns, while boys' remaining turns were more frequently concerned with seeking or conferring status. Findings suggest that valuing the type of interactional work usually done by girls, and helping boys overcome their focus on status would create an environment more conducive to science learning for both genders. (Two tables of data and five footnotes are included. Contains 30 references.) (Author/RS)