Why Teach with Direct Measurement Videos?
As physicists, we analyze events using mathematical relationships, and as educators we would like our students to do the same. Traditionally, three methods are used to present events for students to analyze. First, we use labs, in which students make measurements themselves using an apparatus in a classroom. Second, we use text descriptions, often supplemented with drawings, or sometimes photos. Third, we use demonstrations, sometimes accompanied with measurements.
Each of these methods has inherent limitations. Lab experience is severely limited by practical constraints; we are limited by time and by the relatively contrived situations that we can easily reproduce and measure. As a result, students may only measure and analyze a handful of events in the lab per week, perhaps fewer than 20 situations in a one-semester course. In addition, lab apparatuses often bear little resemblance to objects students encounter in their lives. After all, how often does a student experience an air track in real life? While it is easy for an expert to make the connection between the lab and real life, transfer of knowledge from one setting to another cannot be taken for granted. In the book, How People Learn: Brain, Mind, Experience and School, the National Research Council describes that "knowledge that is taught in only a single context is less likely to support flexible transfer than knowledge that is taught in multiple contexts" (NRC, 2000).
Educators also use word problems to provide descriptions of situations and measurements so students can practice applying physics concepts to a much broader range of events and situations than could be constructed in their lab. Word problems place a written description between the event and the students. But the written description is limited, often, to providing exactly the information, and only the information that students will need to do a prescribed analysis. This has the potential to reduce the realism of the situation and interfere with students' ability to visualize the situation. The National Research Council writes that learning that is "overly dependent on context" can be a hindrance to students' ability to apply that learning to another situation (NRC, 2000). Additionally, if students lack direct experience for the event described, word problems can be particularly confusing and frustrating to them; seeing a video can provide needed context.
Demonstrations allow instructors to present events in class, and to make measurements that students can use. But these are often passive events, and the students' participation is often limited to answering questions and recording data.
Using video to present events for students to analyze provides the potential to overcome these limitations. We can use videos of a wide range of events, even rare events such as the launch of a rocket. We can use high-speed video, or time-lapse video to expand the range of visible time scales. Videos are portable, repeatable, and inexpensive to share. A library of videos can serve as a data set through which students can conduct both structured and more open-ended learning.
National Research Council. How People Learn: Brain, Mind, Experience, and School: Expanded Edition. Washington, DC: The National Academies Press, 2000.