Adding salt to ice : Exploring students' cognitive resources

University students in chemistry and physics were asked to predict, observe and explain what happens when some table salt is poured on an ice cube. Some base their initial responses on everyday events, such as their experience of salt being poured on icy roads, while others try to make predictions based on some scientific knowledge, such as freezing-point depression, and relating energy to breaking of bonds. Some everyday events led to a productive prediction and/or subsequent explanation of the temperature change, and others did not. This was also true for the predictions and explanations based on scientific knowledge. Data is presented and an attempt to explain the productiveness of the reasoning with Redish’s (2004) notions of reasoning primitives (general rules and relationships like “more is more”) and facets (applications of the reasoning primitives, e.g. “larger molecules have a higher boiling point”), and Kuhn’s (2012) exemplars, is made