To analyze a student's conceptual changes, analyzing transcriptions of writing and verbal statements may not provide enough information. In a study of 25 sixth graders learning about matter and molecules, concept mapping of students' stated ideas was used to analyze the kinds of organizational changes the students made to use new science information. Mapping student statements across time should provide insight into the ways they restructure knowledge. Methodology used and findings are reported for 2 of the 25 students as they studied matter and molecules. Interviews, student writings, transcripts of their remarks, and observations of classroom instruction were used to make the concept maps. Maps were constructed by placing each concept in a circle and connecting the circles as concepts were mentioned. Comparing the maps over time reflected changes in student thinking. With the aid of instruction, students organized their information more usefully and their maps became more organized, with more hierarchical levels. Implications for teaching and learning are discussed. Eight figures of concept maps are included. (Contains 24 references.) (SLD)