The purpose of this study was twofold: (1) to understand the conceptual frameworks that sixth-grade students use to explain the nature and structure of matter and molecules; and (2) to assess the effectiveness of two alternate instructional units in helping students change those conceptions. The study involved 15 sixth-grade classes taught by 12…

This paper describes the development of a sixth-grade "Matter and Molecules" unit using a new curriculum development model based on conceptual change research, the field testing of this unit in 15 classrooms and the field test results. The development process and the resulting unit are contrasted with the unit's predecessor, the "Models of Matter"…