On performing concepts during science lectures

When lecturing, teachers make use of both verbal and nonverbal communication. What is called teaching, therefore, involves not only the words and sentences a teacher utters and writes on the board during a lesson, but also all the hands/arms gestures, body movements, and facial expressions a teacher Performs in the classroom. All of these communicative modalities constitute resources that are made available to students for making sense of and learning from lectures. Yet in the literature on teaching science, these other means of communication are little investigated and understood-and, correspondingly, they are undertheorized. The purpose of this position paper is to argue for a different view of concepts in lectures: they are performed simultaneously drawing on and producing multiple resources that are different expressions of the same holistic meaning unit. To support our point, we provide examples from a database of 26 lectures in a 12th-grade biology class, where the human body was the main topic of study. We analyze how different types of resources-including verbal and nonverbal discourse and various material artifacts-interact during lectures. We provide evidence for the unified production of these various sense-making resources during teaching to constitute a meaning unit, and we emphasize particularly the use of gestures and body orientations inside this meaning unit. We suggest that proper analyses of meaning units need to take into account not only language and diagrams but also a lecturer's pointing and depicting gestures, body positions, and the relationships between these different modalities. Scientific knowledge (conceptions) exists in the concurrent display of all sense-making resources, which we, following Vygotsky, understand as forming a unit (identity) of nonidentical entities. (c) 2006 Wiley Periodicals, Inc.