A number of strategies, informed by science education research, have been identified to assist the understanding and communication of difficult concepts in science. A teacher's craft lies in creating learning experiences that facilitate concept development and challenge misconceptions from which students actively build, modify, and extend their conceptual understanding. Concept mapping is accepted as one of several research and evaluation tools that are valid devices for assessing conceptual change. Concept mapping has also been identified by teachers and researchers as a tool for assisting teachers to organize their teaching strategies. Conceptual understanding is influenced by the prior knowledge brought by students to learning situations. Effective teaching entails recognizing students' prior knowledge including any alternative frameworks and adopting teaching strategies to acknowledge those frameworks. Scientific facts, if learned in a meaningful, rather than rote, manner produce much in students' minds. Having identified their students' prior learning, educators are then faced with the challenge of creating learning experiences to facilitate meaningful learning and conceptual understanding. Meaningful communication of concepts can be taught through the use of contexts and case studies; discrepant events (when a mismatch exists between the preconceptions that students bring to a learning situation); analogies, metaphors, and similes; examples and non-examples; and multiple representations of verbal and nonverbal information. Four tables and two figures illustrating aspects of the various teaching methods are included. (Contains 36 references.) (RS)