Discovering the Chemical Mechanism of Common Heating Agents: A Stepwise Inquiry with Student-Designed Experiments in a High School Laboratory Course

摘要

A newly developed laboratory learning program for high school chemistry courses is discussed, in which students discover the chemical mechanism governing exothermic phenomena during the reaction between a heating agent, namely, calcium oxide (CaO)-aluminum (Al) mixture, and water. Based on prior knowledge of simple heating agents such as CaO, the students were able to accurately identify the component chemical reactions in the CaO-Al mixture and water system using three pairs of comparable thermometric measurements arranged in a stepwise manner. In each step, the students designed the comparative experiments for each student group through logical thinking and argumentation to obtain relevant and reliable results. Active interpretation of the results enabled each student to learn the chemical phenomena inherent in the observed reactions, and their understanding was deepened through evidence-based argumentation and debate. Finally, students in each group proposed an overall chemical mechanism governing the reaction between the CaO-Al mixture and water by consolidating the knowledge acquired during the previous inquiry steps. The proposed chemical mechanism was fine-tuned through group presentations, followed by question and answer sessions. The 6-h evidence-driven activity provided numerous opportunities for experiencing the multifaceted aspects of the scientific inquiry process.