This study is part of a larger study of teachers' use of curriculum materials in planning and teaching fifth-grade science. The study focused on one of nine teachers observed teaching "Communities," an activity-based unit from the SCIIS science program (a revision of the original Science Curriculum Improvement Study). "Communities" is designed to introduce students to groups of organisms interacting in biological communities: producers, consumers, and decomposers. Observations of instruction and measurement of learning were completed during teaching of units on producers (plant growth and photosynthesis). Although the teacher became aware that students held certain misconceptions about plant growth, she was unsuccessful in helping them replace their misconceptions with the scientific conceptions she wanted them to learn. The analysis revealed several factors contributing to this disappointing result. Teachers and curriculum developers held different views about learning and the nature of science. In addition, several problems surfaced about the content and organization of the teacher's guide. Implications for and suggestions related to elementary science instruction, development of teaching guides, and teacher education are considered and a list of important teacher education outcomes that should be addressed, such as knowledge of common misconceptions and specific strategies for changing them, is included. (JN)