Research has established that students generally possess conceptions relevant to curricular topics before they begin to study them and that these preconceptions often persist despite instruction on scientific theories which contradict them. Discrepancies between students' post instruction conceptions and the scientific theories as taught often represent important failures of instruction. The existence and persistence of students' preconceptions implies that learning involves not only the acquisition or formation of new concepts, but also modification of existing concepts or their replacement with appropriate alternatives, i.e., conceptual change. Reported are study results that analyzed changes in fifth-grade students' conceptions that did (and did not) occur as they experienced instruction designed to change their conceptions of how green plants get their food. It is noted that the instruction was based on chapters 3-6 of the Rand McNally SCIIS "Communities" unit. The strategy for the instruction sequence of the "Communities" unit is outlined in detail and a discussion of four ways (empirical ambiguity; ambiguity in discourse; attacking the wrong preconception; and loose framing of important issues) in which teaching for conceptual change can go wrong is presented. Implications for analysis and interpretation of empirical studies of conceptual change are also discussed. (JMK)