Monday, June 25, 2018

Quick Electromagnetism Demo Videos

One of my students this past year had a medical condition that required him to be out of school for an extended time. In situations like this, I usually aggregate all the instructional material for a unit into a single file called a Portfolio PDF. Notes, homework, worksheets, quizzes, links to simulations, photos and videos of demonstrations and activities are all in one file. The student can either print everything out, or make changes digitally within the file and send it back.

Portfolio PDF's can only be read by Adobe Acrobat, so the student must download the free Acrobat Reader if it isn't already on his or her machine (as far as I know, the Portfolio PDF cannot be opened in Android and iOS devices yet). You need Adobe Acrobat Pro to create a Portfolio PDF - if you have access to it through your workplace, check it out. Acrobat Pro is worth the investment - get a student or teacher edition with a permanent license for a one-time fee (in other words, just purchase Adobe Acrobat Pro like in the good old days when you actually bought rather than rented software).

One of the units I packaged into a Portfolio PDF is about electricity and magnetism, and in particular about the various devices that take advantage of the E-M interaction. This is a difficult unit for my students, so hands-on equipment is the instructional tool of choice. What was I to do for my distance learner with no access to these devices?

I decided to make quick little videos for him, somehow. I had already been demonstrating the devices for my students, so the devices were out and ready, and I had my explanations practiced and warmed-up. I decided to use a simple Logitech USB webcam that normally attaches to my monitor. I experimented with rigging it up in various ways and hit upon having it point straight down at a black lab tabletop. That way just my hands and the devices would be visible while my voice narrated. The webcam software kept trying to adjust for the black tabletop, over-exposing anything not black. I finally decided to leave something bright in the frame which I knew I could crop out later. This turned out to be a pretty easy way to control the exposure.

After a couple of takes, I opened the video files in my editor of choice, Filmora (again, worth the expense), and edited the video. I created a fade from black at the beginning and a fade to black at the end. I separated the audio track, and faded the audio as well. I went through the audio to get rid of unnecessary um's and ah's and other sounds. Sometimes I inserted a bit of video or audio from another take. It was pretty quick work. I exported the videos as MP4 files and uploaded them to YouTube. The videos are below.

Cross-posted to Teaching Is . . .

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