Students' reasoning about chemical reactions: what changes occur during a context-based post-16 chemistry course?

Abstract

A longitudinal study of 250 students following the context-led Salters Advanced Chemistry (SAC) course explored changes in students' thinking about basic chemical ideas. Students at 36 UK schools and colleges completed the same diagnostic test at the start, after 7 months and 16 months of their 20 month course. Questions probed a range of chemistry topics, including conservation of mass in closed- and open-system chemical reactions, and reacting mass reasoning. Data suggest that many students begin post-16 studies with a wide range of misunderstandings about chemical reactions. However, students' understanding improves steadily as the course progresses. Although some misunderstandings are not addressed explicitly in SAC, these diminish in frequency as students' familiarity with chemical ideas develops. More direct and explicit teaching may accelerate this. Other misunderstandings appear resistant to change despite teaching interventions. This suggests a continuing need to review teaching approaches.