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Teaching physics: Videos instead of midterms

Video problem solutions

By Peter Selkin, School of Interdisciplinary Arts and Sciences, UW Tacoma.

For the past two quarters, I’ve used an approach based on an idea adapted from Andy Rundquist, a physics professor at Hamline University in Minnesota. Instead of a midterm and a final (and in addition to weekly content quizzes), students submit short videos walking the viewer through solutions to physics problems of their choice. Overall, I have been impressed by the solutions students — including those who are struggling in other aspects of the course — submit. Even if the students are getting help from other sources, I see their ability to explain their work on a video as a demonstration of their knowledge.

This approach works best in certain contexts. Most of my teaching is in the introductory physics sequence at UW Tacoma where classes range between 20-40 students. Video demonstrations may not work well for larger classes. The problems require substantial scaffolding for both technical (e.g. posting videos) and pedagogical (e.g. choosing problems) reasons, but that scaffolding is scalable.

Grading is the most time-consuming part of this approach. For that reason, I limit video length to five minutes and cap the number of videos at 10 per student. I have students submit the videos in two sets (five at midterm and the rest at finals), and I watch the videos at 1.5x speed as I grade them. I use a holistic rubric to grade solutions, which also speeds the process. Although grading is time-consuming, it has been rewarding to hear students’ voices on their videos.

For additional information about video problem solutions and other teaching tools Peter Selkin uses, visit his Selkin Lab blog.

Peter Selkin is an associate professor in the School of Interdisciplinary Arts and Sciences at UW Tacoma. As a geophysicist who studies the magnetic properties of earth materials, his scholarship and teaching are at the boundary between geophysics and mineralogy.