A lecture demonstration can be a visually exciting way to illustrate concepts and pique students' interest in physics. Students love seeing physical examples of principles that can otherwise seem abstract and disconnected from the real world. Good demonstrations can be effective in eliciting—and ultimately resolving—students' misconceptions about the physical world. A well-performed demonstration can elucidate a concept in ways that would be impossible to otherwise convey.

Despite their illustrative power, research has shown that demonstrations also often lead to increased confusion.1–4 In many cases, after watching a demonstration, students have an understanding of what took place that is far from what the instructor intended, and students often use their faulty observations of demonstrations to reinforce their own conceptual misconceptions.

In light of these findings, what should an instructor do? Should the use of lecture demonstrations be discontinued for fear of doing more harm than good? How can demonstrations be...

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