How substance-based ontologies for gravity can be productive: A case study

Many science education researchers have argued that learners' commitment to a substance (matter-based) ontology impedes the learning of scientific concepts that scientists typically conceptualize as processes or interactions,such as force,electric current,and heat. by this account,students' tendency to classify these entities as substances or properties of substances leads to robust misconceptions,and instruction should steer novices away from substance-based reasoning. we argue that substance-based reasoning can contribute to the learning and understanding of these very same physics concepts. our case study focuses on a group of elementary school science teachers in our professional development program. starting from substance-based metaphors for gravity,the teachers build a sophisticated explanation for why objects of different masses fall with the same acceleration. we argue that,for conceptual,epistemological,and affective reasons,instructional interventions should focus on tapping these productive substance-based resources when they arise rather than attempting to suppress them. © published by the american physical society.