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2012 August 31

Online physics—what about labs?

Filed under: home school — gasstationwithoutpumps @ 04:31
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I’ve often wondered how online courses handle labs.  Of course, in some fields (like computer science) the tools needed for doing labs are ubiquitous, and there are few safety concerns for doing the labs on your own.  In other subjects, like organic synthesis in chemistry, the safety equipment and supervision needed for many of the labs makes it imperative that students do the labs in a supervised setting.  In between are subjects like introductory physics and electronics, where it is possible to simplify the labs and use low-cost equipment to get most of the benefits of a lab course in a home setting.  More advanced topics in both fields start getting into equipment needs that exceed what an individual would want to buy or be able to borrow.

Since I’m home-schooling my son in calculus-based physics (so far we’ve mainly done mechanics, but this year we’ll be doing electricity and magnetism), I’m particularly interested in how online physics courses handle labs, looking for ideas that I can adapt for our own non-online course.  I found a recent paper by Ann Reagan, published by the Washington Academy of Sciences Online Introductory Physics Labs: Status and Methods.  This paper is a survey of online physics courses, attempting to find out what is being done.

In the intro, they reported 5 goals as desirable for physics labs, based on a position paper by the  American Association of Physics Teachers [“Goals of the Introductory Physics Laboratory,” American Association of Physics Teachers (AAPT), The Physics Teacher, 35, 546-548 (1997)].  Unfortunately, that paper is hidden behind a paywall.  At first I thought that even my university library’s subscription was unable to penetrate the paywall, but that was just bad implementation of the paywall, and I was eventually able to get a copy by editing the URL.  The goals in the original paper are listed as

Summary of Introductory Physics Laboratory Goals
I. The Art of Experimentation: The introductory laboratory should engage each student in significant experiences with experimental processes, including some experience designing investigation.
II.   Experimental and Analytical Skills: The laboratory should help the student develop a broad array of basic skills and tools of experimental physics and data analysis.
III. Conceptual Learning: The laboratory should help students master basic physics concepts.
IV. Understanding the Basis of Knowledge in Physics: The laboratory should help students understand the role of direct observation in physics and to distinguish between inferences based on theory and the outcomes of experiments.
V. Developing Collaborative Learning Skills: The laboratory should help students develop collaborative learning skills that are vital to success in many lifelong endeavors.
Many of the goals are not explicit in traditional laboratory programs. However, the American Association of Physics Teachers believes that laboratory programs should be designed with these five fundamental goals in mind.

I’m in agreement with these goals, though the “collaborative learning skills” will be somewhat limited with just my son and me working together.  (Last year we had another student in the course, but he graduated high school and went off to Pomona.)  I think that the collaborative learning aspects are the least important of the five goals for an intro physics course, as I’ve outlined in other posts on group work.

The first observation in Reagan’s paper is that online physics courses with labs are still fairly rare.  Only about 10% of colleges offered introductory physics online, and 40% of those required the labs be done on-site at the campus, often as intensive weekend or week-long “boot camp” experiences.  That leaves only about 6% of intro college physics courses as attempting fully off-site lab courses.  The paper identified 4 different approaches:

  1. Video analysis of instructor-provided videos.  The instructor designed the experiment, set up the equipment, performed the experiment, and recorded the results on video.  The students used video analysis tools (like the free tool Tracker, which I’ve made some modifications to) to extract data from the experiment and do the data analysis. (Meets goals III and IV, and the data analysis part of II.)
  2. Virtual experiments using simulations (like the well-regarded PhET simulations) are done, with the students interacting with a model of the phenomenon being studied. (Meets goal III and the data analysis part of II, has a flavor or goal I, but without real-world constraints.)
  3. Home experimentation using  loaned equipment or low-cost lab “kits”. (Meets goals I through IV, though only a limited set of the tools of experimental physics will feasible).
  4. Remote labs, where students interact with real equipment, manipulated remotely through the Internet.  (Meets goals II through IV.  Adding goal I would require extremely clever design of the remote operation interface.)

Of these approaches, only the on-site lab and the home experimentation provide the ability to meet the full range of goals. The colleges seem to agree as only 4 of the 400 sites surveyed had simulation-only “labs”.

My own experimentation with home-built equipment last year (see Physics posts in forward order for the full set of posts) leads me to believe that simulation is a terrible substitute for physics labs.  The real-world phenomena are not nearly as clean and simple as the models put into the simulations (even good simulations like the PhET ones), and learning how to get good measurements and model the data appropriately is the point of doing labs in the first place.  A lot of things that I thought would be simple turned out to have unexpected (by me) complexities. Finding ways to get cleaner data by changing the measurement method or the phenomenon being measured was an important learning experience, as was finding models for the actual observations.  Simulation is good for seeing what a particular model predicts will happen, but comparison to what actually happens is essential.

Reagan chose to explore the “kit” approach further, probably because she also believes that it is the only pedagogically acceptable alternative to the on-site lab (though she is careful not to say so).  She

limited consideration to experiments that 1) were relevant in scope and content to the curriculum of a first-semester introductory physics course, 2) were of appropriate complexity and depth for a college-level course, 3) would provide sufficient accuracy for student analysis and student satisfaction, 4) could be accomplished semi-autonomously by college students in a distance format (e.g., from home, communicating with instructors via e-mail or online chat, only), 5) required direct, hands-on interaction by students with the experimental process, and 6) could be accomplished with inexpensive or readily available materials at a total cost to students for ten such experiments commensurate with the price of a single textbook.

One suggested lab approach that I didn’t use last year, though I would have if I’d thought of it,  is using a microphone and sound software like Audacity for doing timing measurements.  She mentions timing dropped balls and bouncing balls by this approach.  It is probably easier to get clean data for estimating the coefficient of restitution from the times of the bounces than from the long exposure time digital photography method my son used in his fifth grade science fair project, though not as visually appealing. I think that our use of the Arduino for timing (for example, in the speed of sound  lab and the pendulum lab) was at least as effective, and did allow us to use triggers other than sound.

She also talks about using cell phone video cameras, frictionless pucks sold as toys, and Tracker video analysis for some of the other motion labs.  We did not end up doing much video analysis last year, because it was tedious and not well suited to any of the labs we ended up doing.  There were a couple of labs where it might have been a good idea instead of the methods we tried instead.

Interestingly, their first attempt at the Audacity lab for measuring the time for dropped balls was a failure in the real world:

Misunderstandings, misconceptions, and computational errors resulted in student-demonstrated percent errors ranging from 2% to 35%, despite consistent achievement of experimental errors of 1% to 2% in the same experiments carried out by the instructor.

They got much better results when they added video instructions for the labs that addressed common misconceptions and had the students working in a lab where they were observed by an instructor (even though the instructor was not supposed to answer questions). I wonder how much of the improvement resulted from the video instructions and how much from being observed.


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