Identifying and improving students' mental models of tooth decay

Abstract

The aims of this study were to identify the initial mental models of tooth decay among a sample of 15-16 year-old Spanish students, and then to analyse changes in these models following the students’ participation in a teaching sequence on this topic. The study focuses on the analysis of two tasks that formed part of a pretest/ post-test design whose aim was to determine whether students could provide an adequate explanation of the problem of dental caries. Mental models were identified through an iterative process that combined an examination of the nature of the concept in question with an analysis of students’ responses. Five mental models of tooth decay were identified. Three of them were associated with a single active agent (the tooth, food or microscopic living organisms). The fourth model included sugar plus a second active agent, while the active agent in the fifth model was acids. We also identified four mechanisms, which were not exclusive to any one model. The results showed an evolution in students’ explanatory models of tooth decay following their participation in the teaching sequence. Initially, the majority of students used simple models involving a single active agent, whereas by the end of the teaching sequence the majority of them were employing the most advanced models. However, formulating the mechanism through which tooth decay develops remains a complex task for students, particularly as regards understanding that the interactions which produce the active agent and its action upon a tooth are chemical reactions.