Spring semester ideas and questions

I did another Piper Physics Patrol show today, but the best part of the day was the drive home. I brought a student with me, as all physics majors are required to do at least one show with me before they graduate. She was in my fall SBG-based class and is registered to take my spring Physical Optics course (syllabus from 2 years ago here). She also took two of the courses I’m teaching this spring, last spring. It was a 45-minute drive that really got my brain going on some ideas for my spring classes and I wanted to get some of the ideas and questions down here, in the hopes that you can give me some feedback on them.

LabVIEW out, Arduino in

In the spring of their sophomore year, physics majors take Modern Physics. I regularly teach the lab portion of that course. The work is about one third famous labs, one third learning computer control of equipment, and one third a “fake data” project. Here I want to talk about the computer control third.

For the past 11 years, I’ve first taught the students the basics of LabVIEW, and then had them use LabVIEW to control motors, read thermometers, and play with things like accelerometers. Then they have to build up the LabVIEW for the fake data project. Here are a few pros and cons of this approach:

  • pros
    • LabVIEW is powerful and looks good on a resume
    • We have a site license for 20 machines
    • LabVIEW works well with Vernier probes, of which we have a lot
    • There’s very little LabVIEW can’t do when it comes to computerizing an experiment
    • There are lots of good examples bundled with LabVIEW
  • cons
    • We ONLY have a site license for 20 machines
    • LabVIEW is a little overkill for measuring a single voltage
    • Our students don’t seem to embrace LabVIEW in their junior-year projects
      • Here I think I mean that they don’t feel comfortable enough with it but it might be the 20 license thing
    • LabVIEW is constantly upgrading and backwards-compatibility isn’t a strong suit of National Instruments

Last summer I had a student working with Arduino boards to see just how much of our Modern Lab curriculum it could handle. It turns out, it’s quite a bit! Here are some pros and cons:

  • pros
    • Cheap ($30 for board, another ~$50 for the motor shield, free software)
    • Easy install on macs and pcs
    • controllable by Mathematica
      • My student figured most of this out last summer
      • We have a campus-wide site license for Mathematica, including any computers that belong to students
    • Decent set of examples online
    • set it and forget it
      • you can install your script and hit go and it’ll just keep doing it without further computer interaction
  • cons
    • It can’t easily produce a true adjustable analog output
      • It simply changes the duty cycle of a repetitive 5V pulse to achieve a different average voltage value
    • It can’t easily communicate with gpib and serial devices
    • The data rate back to the computer is slow and there’s little onboard storage
      • My student worked with an SD-card shield that works well but the triple stack of Arduino, motor shield, and SD-card shield was problematic
    • The suggestion of using Processing to collect and plot data is kind-of a pain because the processing code looks daunting to students

So, after talking with my student today, I’m very much leaning toward changing the curriculum entirely to Arduino, including the fake data project. One of the things she pointed out to me was that, last summer, she had to use LabVIEW to control an instrument in the lab she was working in. While it was true that she’d been exposed to it in my class, she really didn’t feel she learned how to use it until she had a true project to do. I asked her how much she would have been slowed down if she hadn’t learned LabVIEW last spring. She thought it would only have been as much as a week.

I also talked to her about a point I mention above. I asked whether her current cohort of juniors in the advanced lab were willing to embrace LabVIEW for their year-long projects. She reported that few of them were, because they don’t feel comfortable with it and because they’re slaved to the computers we’ve installed LabVIEW on.

So what would have to change? I break my LabVIEW training down into voltage in, voltage out, motors, and combinations. Those are pretty broad and they’re usually exposed to enough to see how to do complicated things. Arduino can handle most of that. Certainly the voltage in works fine. The voltage out is problematic as noted above, but the duty-cycle solution is fine for things like dc motors. It’s not-so-fine for things like the photoelectric effect lab. The motor shield we’ve purchased for our Arduino’s seem to make the motor stuff much easier on the Arduino than LabVIEW. As for the fake-data lab, I think there may be a few projects I’ll have to steer them clear of, but not many.

I’d love to hear what you think about this change.

Lab standards

My student asked me how I was planning to do Standards-Based Grading (SBG) for a course with a lab, something I haven’t done yet. I told her I was still kicking some things around. Here are some of the possibilities she and I debated and I have been thinking about. I’d love some feedback from you about them.

The lab is the standard

“I can can do the index of refraction of a piece of glass lab.” That could be the standard and maybe they have to all do it on the same day in lab.  It would include error analysis, plotting, data collection, formal write-ups etc.

The idea is the standard

“I can measure the index of refraction of a piece of glass.” There will be a lab day devoted to it, but maybe they don’t have to do it/finish it that day. It’ll still include things like error analysis etc as listed above.

Lab skills are separate

“I can propagate errors through a calculation.” Every lab will have this so every lab will get a score for this. By my normal procedures, that would mean their last lab would be the only one that counts. Problematic, I suppose.

Labs are individual

“I can be a group leader” and “I can be a Laboratory Assistant.” Everyone has to do every lab by themselves, unless more hands are needed. The lab standards would likely be like “I can measure the index of refraction of a piece of glass” along with “I can propagate errors.” If they need more hands, they’re assessed on how they function in a group with very particular roles assigned. Sometimes they’re the leader (when they’re gunning for the lab standard). Sometimes they’re the lab assistant (when they’re simply gunning for the lab assistant standard).

A big problem with this latter one is that they might have to do a few labs several times, once as a group leader, and a few times as an assistant.

I like the individual approach to labs because then they can reassess them with easier logistics. Of course, then I have to make the labs quite modular from an equipment perspective.

I’d love some feedback on these ideas. I don’t have to pull the trigger for 3 weeks. Thanks in advance!

About Andy Rundquist

Professor of physics at Hamline University in St. Paul, MN
This entry was posted in lab, physics, sbg. Bookmark the permalink.

18 Responses to Spring semester ideas and questions

  1. John Burk says:

    What is the piper physics show?

  2. bwfrank says:

    Maybe consider doing labs skills with an adjustment for sustained proficiency… so it’s not enough to ping the standard one time, even if it’s at the end?

    • Andy "SuperFly" Rundquist says:

      yeah, I like that idea. I know that in my normal not-SBG lab approach that’s what basically happens.

  3. bretbenesh says:

    Hi Andy,

    I don’t know much about physics, so take all of this with a grain of salt.

    1. I have never used it, but the Arduino seems cool.
    2. I like “Labs are individual” and “the idea is the standard” much better than the other two. Could you cut down on the number of labs, identify the most important labs, and make the repetition of lab work a benefit? There are probably labs that would be beneficial to see more than once, right?

    • Andy "SuperFly" Rundquist says:

      Hi Bret,
      I’ve really been thinking about what the core important things are for lab. Certainly the seven or eight I have planned (some take 2 weeks) tie closely into the material we’re planning to cover in the lecture portion, but maybe that is trumped by notions of necessary lab skills, etc.


  4. Melissa says:

    I’m not exactly doing SBG, but I’m trying something that inches towards that direction in my electronics class this term. I’m requiring students to do performance assessments. These ask students to show that they understand both the theory that we’ve talked about in class and the experimental techniques that they’ve done in lab. For example, one of the performance assessments might be “I can evaluate the Thevenin equivalent R and V for a circuit.” In the performance assessment, the student will be shown a drawing of a circuit and asked to do the calculations to predict what the Vth and Rth is for the given circuit. Then the student will be asked to build the circuit shown, measure Vth and Rth, and test whether the experimental results agree with what they found in their calculations. If the two don’t agree, the student can then either revisit their calculation or re-do their experiment. As I said, my classroom isn’t a pure SBG classroom, and this is the first time I’m trying this, but I think something like this might work for your class. For what it’s worth, my students do all their electronics labs alone, and these performance assessments will also be individually done.

    • Andy "SuperFly" Rundquist says:

      Hi Melissa,
      The performance review sounds really cool. What are the logistics of it? How often? Who initiates it (student or you or either)? How much do they affect the grade?

      • Melissa says:

        Here’s how the scheduling works: After we’ve covered a section, I list one or two topics that are subject to performance reviews, and within two weeks of posting those topics the students must schedule to come in and do the performance reviews. I’ve never tried this before and it’s still early in the term so we’ll see how it pans out. I’ve made these 20% of the grade in the class. (They replace quizzes.) I’m both excited and scared to see how it all works out.

  5. Melissa says:

    Oh, and one more thing. I’ll be using Arduinos for the first time in the electronics class so I’d be more than happy to trade tips.

    • Andy "SuperFly" Rundquist says:

      Do the Arduinos replace old-school things like 555 timers etc or are they meant to act as multimeters? Or maybe something else entirely? I’d love to compare notes!

      • Melissa says:

        We have these 6502 microprocessors that had been used for the digital portion of the course, and I’m planning on having the Arduinos replace/complement those.

  6. paul lulai says:

    I’ve faced some of the same issues with labview. I believe there is a much less expensive version available to students for their own computers. That could help the access issues. Maybe this cost could be wrapped up with their book prices. Maybe not.
    The seemingly infinite number of menu options is rather intimidating. I’m sure you suggested it, but pinning a frequently used menu to the work screen is helpful.
    I believe NI has started to produce more video tutorials and samples within just the past 8 months. It might be helpful to see what they’ve produced. I know they now have the site k12labs.com (or something similar). While the labs may not be on par with the work your students are doing, the samples might be helpful.Backward compatibility is still absolute crap.
    Good luck.

    • Andy "SuperFly" Rundquist says:

      Hi Paul,
      I used to require students to buy the student version of labview along with a low-end DAQ device that NI bundled. It was about $150. I found that the majority of my students either didn’t buy it or put it off much longer than was useful for me.

  7. Joss Ives says:

    Hi Andy, I have feedback for both the main topics. I love how much our teaching load seems to overlap.

    Since your students are reasonably well-versed in Mathematica, that does seem like the logical software side for using Arduino as a DAQ device. So instead of having to deal with the double new paradigm of learning LabVIEW (where most students have never worked in a visual programming environment) and learning the intricacies of DAQ, they can focus their efforts on learning the intricacies of DAQ and work in a comfortable computing environment. Sounds like a win!

    Onto SBG in the lab…

    If you consider skills such as error propagation to be something that they should demonstrate for each lab, then I think you have to go with assessing each of these types of standards for each lab. I will propose a system based loosely on what I am doing in my Advanced Lab course. Ultimately it looks like a well-communicated rubric for each lab with the opportunity to re-assess, which is more like traditional grading with some SBG flair.

    So for each lab you have a rubric that has broad (to the course) and specific (to that lab) standards.

    I can propagate errors
    I can follow all the nit-picky details regarding presenting graphs, etc
    Whatever other skills you think are important enough that they should be graded

    I can measure the index of refraction of a piece of glass.
    I can discuss ways to improve this measurement
    I can answer pre-lab question X
    I can answer follow-up question Y

    Perhaps you are assessing them based on their lab reports, short oral presentations or lab notebooks. You grade each standard on your regular 0-4 scale and give them a net grade for the lab.

    But the key is that they can always reassess an individual lab (or portion of the lab if the chosen method of communication allows). I use a weighted average leaning toward the reassessment so that they don’t just feel like they can hand in the dog’s breakfast and get the feedback needed to make it wonderful without being help somewhat accountable.

    Why this looks like SBG to them. They are seeing specific and explicit expectations being communicated to them in the student-centered language the have come to know in your other SBG courses “I can…”. They are also being given opportunities to re-assess.

    • Andy "SuperFly" Rundquist says:

      Hi Joss,
      I find I’m often channeling my inner-Joss when working out these sorts of details. I like your approach, but I know that I really have to decide some big picture things soon, like whether they can repeat labs, whether they need to do them all on the same day (to fit better with the lecture) etc.

  8. Pingback: Labs in SBG | SuperFly Physics

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