Why not just run this as a demo? Differences in students' conceptual understanding after experiments or demonstrations

Abstract

Chemical engineering enrollments have ballooned in the past five years, making it increasingly challenging to find physical space for undergraduate student laboratory experiences. Rather than have laboratory sections with core chemical engineering courses such as fluid mechanics or heat transfer, most students' in-major laboratory experience is limited to a unit operations laboratory course. Our previous work demonstrated that inquiry-based laboratory activities, brief hands-onexperiments designed to directly combat common misconceptions, could be highly effective at repairing students' misconceptions. However, even brief experiments present logistical challenges for many colleagues. Therefore we undertook a study asking the question: What is the effectiveness of the same activities if performed as demonstrations? Over 200 heat transfer students at three institutions were given the Heat and Energy Concept Inventory (HECI) at both the start and end of the semester. During the semester, instructors either had students complete four brief laboratory experiments designed to repair common misconceptions in two areas of heat transfer or had students watch demonstrations of the same experiments as demonstrations. Both treatments were accompanied with the same pre-lab prediction questions and post-lab assessment and reflection questions, which kept student time devoted to each activity similar. Students performing the experiment in small groups scored higher on the concept inventory than did students who watched a demonstration (24.7-percentage point increase relative to 16.9-percentage point increase) although both groups improved significantly relative to their pre-test scores. Analysis of the student reflection questions mirrored this trend, with students performing experiments answering the reflection questions more fully and more correctly than students who watched the demonstration.