Examines third-grade students' ideas on the lunar phases prior to, and following, an instructional period designed to promote students' conceptual change. Demonstrates that students are capable of making conceptual changes. Contains 30 references. (DDR)

Reports on a study that uses psychometric modeling to rank the appeal of a variety of children's astronomical ideas on a single uniform scale. Findings support the view that alternative conceptions may be markers of progress toward understanding. Contains 82 references. (DDR)