Is it natural or processed? Elementary school teachers and conceptions about materials

This paper explores the science content knowledge of elementary school teac hers, and its possible role in helping them teach effectively. These issues are explored in the context of an investigation of the views of 106 elemen tary school teachers who had participated in professional development cours es which focused on the topic "natural and processed materials." These prac tising teachers revealed a range of conceptions about materials, which have been categorized into broad types. Some of the teachers showed shifts in c onceptions, from what could be described as "naive" conceptions to more sci entific views, after a 2-day professional development activity. (C) 2000 Jo hn Wiley & Sons, Inc.