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February 6, 2015

Using Direct Measurement Videos to Teach Rotation

I'd like to share with you a tool I've just fallen in love with: Direct Measurement Videos.  These videos are produced by the Science Education Resource Project (SERC) at Carleton College by Peter Bohacek, Matthew Vonk, Ellen Iverson and Karin Kirk. The videos are short, high-quality, slow-motion videos of real events. The videos have scales drawn on them so students can measure distances and angles. They also have a frame counter so students can use them to measure time.  Other data is provided as needed.

I heard of these videos probably over a year ago, but as with most things I encounter at AAPT or other professional development, repeated exposure is required before I am ready to adopt it and use it in my classroom. I believe that hands-on labs are the best types of labs, and I believe that video analysis is a wonderful way to make measurements of all kinds of motion, particularly motion in two dimensions.  But sometimes the content doesn't lend itself well to hands-on labs: universal gravitation is one topic that comes to mind. For this type of content, simulations can be helpful. Direct measurement videos can serve as an additional lab after a hands-on lab; they can be used to lead a class discussion; and they can be used as homework. Using these videos as an alternative to the traditional book problems encourages deep conceptual understanding as it requires the students to decide what to measure to answer the question, rather than just using the numbers they are given. I have used them for all three purposes in the rotation unit alone.

I started the rotation unit with a DMV homework assignment related to measuring and calculating angular velocity and acceleration.   Then we did a hands-on lab about rotational energy using soup cans, and another hands-on lab about torque using a T-shaped device made with PVC (based on Connie Wells' apparatus). After those were completed, we used DMVs to study angular momentum.   This time I gave them an activity that started as "lab" in groups in class, and was to be completed at home. They made measurements on a video of a disk-on-disk collision, verifying that angular momentum was conserved, and that kinetic energy was lost to thermal energy via friction. They also made measurements on a video of a rocket accelerating a disk. And finally, I used the "Marble and Block" collision to lead a discussion of a collision in which both linear momentum and angular momentum are conserved.

When you get a chance, take a look at these videos. Many of them come with activities already prepared. And it doesn't take long create your own assignments for students based on these videos. Good luck and have fun creating!

1 comment:

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