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14 July 2014

Direct Measurement Videos

Youtube has been a staple of the physics classroom for a while now.  There's no shortage of interesting videos to analyze, some of which are specifically created for science purposes.  My favorite of the produced-for-science infotainment genre is probably the Smarter Every Day series.  Take a look at the episode about how cats land on their feet.  It's got amazing footage, an entertaining host, high quality production, solid physics, and CATS!  I wouldn't use this video as a teaching tool, though.  My in-class demonstrations and labs are never designed purely as a show.  Everything I set up in class has a quantitative predictive element.  My students will certainly enjoy Smarter Every Day, but as a supplementary extra-fun part of learning physics, not as something integral to the course.

So can a video series possibly be integral to an introductory physics course?  Yes.

Take a look at Direct Measurement Videos, a series produced by Peter Bohacek, Matthew Vonk and several other Wisconsin physics teachers.*  Each video in their library shows live footage of an experiment.  Post-production work provides enough information to make, well, direct measurements.  For example, the frame number and frame rate are displayed prominently.  Where appropriate, a length scale is superimposed on the action.  Multiple camera angles are shown when useful.  

* The full credits on the site list Peter Bohacek, Matthew Vonk, Ellen Iverson, and Karin Kirk.  I mention Matthew in particular because he was my table leader at the AP Physics reading.  Most of the videos seem to be credited to Peter.

While the production quality is solid, Direct Measurement Videos are emphatically NOT edited for infotainment purposes.  You won't see a narrator.  Many of the clips would seem humdrum to the non-physicist: a car braking on an ice rink, a marble colliding with a wooden block, a doll rotating on a turntable.  The excitement of these clips is that they bring to life the end-of-chapter problems that we've been assigning for decades.  

Aside:  I got myself in trouble at a consultant meeting when I cheeked a non-physics-teacher presenter.  His brief speech was full of enthusiasm but empty of substance -- I wanted to get back to talking physics teaching.  The guy kept going on about how we as consultants should emphasize real-life physics.  So I raised my hand and asked him, "Could you please give us an example of physics that is NOT 'real-life' physics?"  The reaction was as if I had cited Adam Smith at a 1980 Moscow State University economics department meeting.

Of course all physics is "real-life."  The central tenet of my own teaching has been to highlight the experimental nature of physics problem solving, to the extent that I refer not as much to the "answer" to a problem as to the "prediction" made by the problem.  I set up quantitative demonstrations that have little wow-factor, but which verify the prediction made by in-class example problems or homework problems.  

Direct Measurement Videos have taken that philosophy to a whole new level.  In class, I'm limited to the equipment I own, the space in my classroom, and the tools (such as Vernier's live computer data collection) that allow for immediate analysis.  DMVs have no such limitation.  They can show a roller coaster at 200 frames per second -- I have no nearby roller coaster.  They can show the slow-motion, frame-by-frame results of a dart sticking to a cart -- while I can do that experiment, I analyze with Vernier motion sensors only, and my students can't repeatedly rewind the live action to see the moments before and after collision.

My intention is to use a Direct Measurement Video about once a week as a homework problem in a different sort of "flipped class."  Traditionally I've assigned a textbook-style problem for homework, and then we've set up the physical situation in class.  Now, though, I can have the students work through a textbook-style problem in class to make a prediction, then assign the data analysis off of the video as homework.  Or, rather than assign a problem which gives all relevant input data, I can link a video and say "determine the coefficient of friction between the doll and the surface."  The students have to do more than just make a calculation; they have to figure out what data must be acquired to make that calculation, and then they have to figure out how to acquire said data from the video.  We can get away from the idea of physics problem solving as putting given numbers together in the right equations; we can get away from the idea of laboratory as a separate, distinct, disconnected portion of a physics class, instead integrating predictive and experimental physics on an everyday basis.  Wow.  Thanks, Peter, Matthew, et al.


2 comments:

  1. Hey Greg,

    Thanks for highlighting our videos! It's funny, as hard as Peter Bohacek and I try to characterize the distinction between what we do and the other options out there: e.g., the videos that you call "infotainment", student-made videos, simulations, hands-on-labs, and written homework problems, I don't think we've ever put it quite so elegantly as you have. You totally nailed it.

    "I have no nearby roller coaster"

    "my students can't repeatedly rewind the live action to see the moments before and after collision."

    "physics is "real-life""

    "The students have to do more than just make a calculation; they have to figure out what data must be acquired to make that calculation"

    "...and then they have to figure out how to acquire said data from the video."

    "we can get away from the idea of laboratory as a separate, distinct, disconnected portion of a physics class, instead integrating predictive and experimental physics on an everyday basis. Wow."

    Wow to YOU! I love the way that you write.

    ...any chance you'd be available to help write the next grant proposal?




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  2. Thanks for the kind words, Matt. Please use everything I've written here if it helps with your next grant. I couldn't be more impressed with the work that you and Peter and your colleagues have been doing. Your videos have been a huge hit with teachers at my AP Summer Institutes.

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