Uncomfortable Questions: Physics Curriculum

Johan Larson asks:

How would you change the requirements and coursework for the undergraduate Physics major?

This is a good one, but it’s a little tough to answer. I have ideas about things I’d like to change locally, but I’m not sure I really have the perspective I would need to be able to say how much of what I see is a problem with physics education in general, and how much is due to local quirks (our trimester calendar being the biggest such issue) that don’t generalize well.

That said, my feeling is that most of the problems we have are with the introductory classes. I went to an American Association of Physics Teachers workshop on calculus-based intro physics a few years back, and one factoid mentioned there really stuck: Only about three percent of students who take introductory physics ever take another class in the subject. That’s pretty dismal.

My general suggestion regarding reform of introductory physics classes is that the goal should be to make them look less like high school physics.

This is a huge problem with the introductory mechancis classes that I’ve taught here, and it hits the best students the hardest. The standard curriculum for introductory college physics is pretty much indistinguishable from a good high school class: you do kinematics, then Newton’s Laws, then energy, then momentum, and so on.

The class looks extremely familiar to any student who has had a good high school class, and as a result, many of the best students just… shut down. They’ve seen the basic material before, and they did well with it the first time around, so they can just coast through the first two-thirds of the class without really needing to engage their brains. This later comes back to bite them in the ass, when we finally do hit material that’s new to them, because they’ve let their study habits atrophy, and so some really bright kids will crash and burn when we hit vector angular momentum, as they’ve gotten out of the habit of doing the reading and homework.

Most of the students in our introductory classes come in thinking that they’re going to be engineering majors, and the just-like-high-school approach doesn’t encourage them to change their minds. The engineering departments run an intro class that’s based around projects and real problem-solving, while we’re hitting them with block-on-an-inclined-plane problems that they’ve seen before. It helps solidify their impression of physics as some boring drudgery that you need to get through in order to do the cool engineering stuff.

I don’t have a single reformed curriculum that I strongly prefer, but I’m in favor of just about anything that would shake things up. We’re trying that this year, using the Matter and Interactions curriculum developed by Ruth Chabay and Bruce Sherwood, which starts off with the relativistic expression for momentum as the first equation in the book, and uses a lot of numerical simulations in VPython to teach intro mechanics. I’ll be teaching E&M out of that starting a week from Monday, and it’ll be an intersting change of pace.

I’ve also gotten a lot of good stuff out of the Six Ideas that Shaped Physics books by Thomas Moore. These are based around a handful (plus one) of simple central organizing principles– “Conservation Laws Constrain Interactions,” “Electric and Magnetic Fields are Unified”– and use those as a framework for presenting the usual topics in a different way. It’s a less radical departure than Matter & Interactions, but it’s still not at all like the typical high school class.

In both of these cases, the material is presented in a manner that’s much closer to the way practicing physicists think about physics. The Matter & Interactions curriculum maps very easily onto numerical approaches to physics theories, while Six Ideas highlights the centrality of conservation laws and unification of forces. They both offer richer, more engaging approaches to the material, that give an earlier hint as to why somebody would consider physics for a major or a career.

And, most importantly, they’re different enough from the usual approach that even students with a strong background won’t feel like they’ve seen it all before. It forces them to engage with the material a little more, if only to see how to re-arrange the concepts that they learned in high school to better suit the new presentation. That should keep the better students a little more involved, and might help to show them that physics is more than just memorizing lists of equations.

When you get past the introductory level, the best approach really depends on the department and its resources. Particularly at a liberal arts college, where students generally have outside requirements that limit the number of courses they can take in the major, you won’t necessarily be able to teach the same breadth of topics as a major research university, and you need to make some choices. When I was at Williams, for example, they had a large concentration of faculty doing research with lasers, and they made the most of that by working optics all through the currciulum. This played to the strengths of the department, and I think I have a better feel for a lot of quantum-optical phenomena as a result.

Of course, there’s always a trade-off with this sort of decision– in this case, they didn’t have anybody to teach nuclear and particle physics, so my knowledge of those areas remains very hazy to this day. But that’s ok– the world needs atomic and laser physicists as much if not more than particle physicists. There are other schools where they teach nuclear physics throughout the curriculum, and never really deal with optics at all.

The introductory classes are the closest thing to a standard curriculum across all schools, so they’re the place for general reform. And as far as I’m concerned, just about any reform is good, as long as it doesn’t look like high school physics.

18 comments

  1. Great introductory coursework is great, but it’s of little good if the juniors and seniors end up in looser classes. In particular, it always amazes me how bad quantum mechanics classes are. The math is far easier than in E&M or analytical mechanics, yet students feel as though they are underwater the entire semester.

  2. Great introductory coursework is great, but it’s of little good if the juniors and seniors end up in looser classes. In particular, it always amazes me how bad quantum mechanics classes are. The math is far easier than in E&M or analytical mechanics, yet students feel as though they are underwater the entire semester.

    With quantum, a lot of the problem is just that the material is so far removed from everyday experience. With classical mechanics, even when the math gets hairy, you can fall back on physical intuition. That takes a while to develop in quantum physics.

    I think there’s also a bit of a problem with quantum physics in that there are two very different approaches to it, either via the Schroedinger Equation and the language of differential equations, or via operators, commutators, and lienar algebra. Both are useful, and practicing physicists need to use both, which leads to some awkward switching back and forth when the subject is first introduced.

  3. Hi Chad,

    If the Physics First idea ever takes off, a lot of this may change since there will be at least a couple of years between high school and college physics. But I can’t really see that kind of massive institutional change happen, if only because AAPT lobbies for physics education reform through its members, not through state or federal departments of education.

    Someday if I ever get some guts I’m going to try to teach my (high school) course starting at conservation of energy and working backwards from there. I think it would work, but every single high school text does it the traditional way so it would be hard to convince parents and administrators to go with it.

    By the way, I started reading this blog via other science blogs, and had no idea that you were two miles down the street until I saw the word “Niskayuna” in one of your recent posts. Locals represent!

    jim.

  4. Introductory stuff is very different now. If I could change anything, it might be to get more quickly to exciting stuff. Classical mechanics is so bloody dull compared to other things. The various ways to make the classe more interactive are fairly successful particluarly with this generation of students. The biggest two things are to convince people that there is not a world of physics and a world of reality (slide something and it stops, so much for “what is in motion remains in motion”) You have to make sure they get the “unless acted on by an external force” part. Also that physics is a whole, not just mechanics OR thermo OR E&M, and to capture the way of thinking, reasoning, and problem solving that is needed. People are drawn because of nano, quantum computing, black holes, particles, all the cool stuff. And they spend the first year doing stuff that is literally 100 years old!!! Bah!!!!!!

    The lecturer can add new stuff, or applications of old stuff to new stuff. Books that just add in a brief section on laser cooling or something, well they don’t read that unless you put those questions on the test!!!!

    I think you could teach a whole semester or two based on laser cooling, or some other aspect, or break it up like the Thomas Moore book Chad mentioned.

  5. I think you could teach a whole semester or two based on laser cooling, or some other aspect, or break it up like the Thomas Moore book Chad mentioned.

    I forgot to plug Colgate’s Modern Introductory Physics approach. Their first course approaches everything through the question “How do we know that atoms exist?” They do a lot of “modern” physics up front. It’s an interesting idea.

  6. Only about three percent of students who take introductory physics ever take another class in the subject.

    If the methodology was such that it included intro physics classes required by pre-med, engineering, or other curricula… then it included a large number, probably a majority, of students who never intended to concentrate in physics in the first place. In those cases, the course failed to ignite interest where (usually) none existed, but it would be incorrect to conclude that such courses killed existing enthusiasm in 97% of students. Not that you presented it this way, but I think it’s worth pointing out.

  7. People are drawn because of nano, quantum computing, black holes, particles, all the cool stuff.

    Black holes are difficult to study with tabletop experiments. 🙁

  8. If the methodology was such that it included intro physics classes required by pre-med, engineering, or other curricula… then it included a large number, probably a majority, of students who never intended to concentrate in physics in the first place.

    True enough, but the factoid isn’t the number of people who become majors, it’s the number who take another class, even as an elective. I suspect that a fairly high fraction of those who do take another class end up being majors, just because the numbers are so small.

    I’d like to see more and better physics majors, but I’d also be happy to have people leaving the requied classes with a higher opinion of the field than that. As it is, there are a lot of future engineers and doctors who think that physics has nothing to offer but blocks sliding on inclined planes, and that’s really a shame.

  9. ah yeah, Charlie Holbrow’s stuff.

    And Johan, you don’t need black hole labs. Course you can do a lot of that with fiber optics!

    I don’t care if they take more physics IFFFFFF they go away knowing about what science is, what do we know, and why do we think we know it! No people riding dinosaurs

  10. Back in the dark ages (the 1980s) I had to do Newtonian physics etc three years running (I was an exchange student for a year at high school) and all three courses were almost identical even though taught in different parts of the world. But I don’t recall being bored. I loved it. I got to do special relativity, and every time I did it I understood it a bit better. But I understand that I was bit of a freak. You’re right: something needs to be done.

  11. Your average SAT score of 1240 (before it was dropped) is not a trivial matter in this discussion. It might be higher for the students in your physics class. A couple of questions here; my comments will be made separately.

    1) What is the first-day Force Concept Inventory score of your students? If you don’t do this normally, try it once just to find out. I’ll bet it isn’t 33. This is probably as big a deal as the verbal scores your kids come in with.

    2) Do you require calculus 1 as a pre-req and calc 2 as a co-req, or do they take physics with calculus?

    3) What percentage of your students took HS physics?

  12. A couple thoughts, in no particular order. OK, more than a couple. I think I will also copy this into my blog.

    1) Compare the number of BS engineering degrees to the number of BS physics degrees and your 3% number is easy to understand, particularly when you consider the number of electives in a typical engineering program [zero].

    2) One way to increase that number is to offer a “concentration” (if not a really minor minor) in physics that only requires a third course in modern physics. This can be popular with EE and computer engineers like you have, also materials science. Heck, *you* could tailor it to modern physics with an emphasis on (a) quantum mechanics, (b) lasers and AMO with a teaser about optical computing, (c) enough nuclear physics to be educated about the difference between a bomb and a reactor, (d) enough relativity to discuss astro topics and/or QED. You ought to get at least one extra major a year out of part b alone.

    3) I agree 100% with #1 about QM. I evolved from a math undergrad to a physics grad student because I got hooked by a great freshman QM class that made the subject intuitive (to me, at least). If there is an area that needs reform, that is it. Why should the first “majors” class be intermediate classical mechanics?

    4) I am under no illusion that I am teaching mostly engineers at my CC, and I pitch the class that way, yet I have managed to produce some physics majors … one of whom is applying to grad school this year. Could it have helped that I don’t pretend that I am teaching “real” physics and frequently allude to the things you could work on when you do, as well as the next level problems my engineers will have to solve?

    5) One of the other things that hooked me into physics was the nearly miraculous agreement between the solution of a system of coupled DEs for a double pendulum and a demo of same. This was also in the freshman sequence I took (out of the old Berkeley course that I saw used recently at MIT). The key there was a bit of non-trivial math explaining reality (really well) rather than a qualitative demo or ‘easy’ math problems.

    5a) If you want to wake up your class, start out with F=ma and do an un-driven damped oscillator in the second week? Using a complex solution to the DE? Then do the pendulum out to the cubic term in the series? Then do the coupled system of two oscillators, with each of these tested by experiment.

    6) Part of every class coasts through the first part of the 1st semester, but my survival fraction would fall significantly (maybe by a third or more) if we did not spend time on kinematics and problem solving. [My answers to the three questions I posted are quite different from yours, I am sure.] I cannot start with challenging modern concepts when most of they are still being challenged by word problems that generate two equations in two unknowns.

    7) My response to the view that physics is about memorizing equations is to note that it should be about problem solving with a handful of equations. No one should give the “range” formula in a freshman textbook or use the elastic scattering equations. The students will only work from first principles if you do. And it does not hurt to give exam problems that have a symbol or three in the answer rather than just a number from a calculator just to be sure they can solve an equation without graphing it.

  13. The class looks extremely familiar to any student who has had a good high school class, and as a result, many of the best students just… shut down. They’ve seen the basic material before, and they did well with it the first time around, so they can just coast through the first two-thirds of the class without really needing to engage their brains.

    This sounds like a special case of the problem that the handoff from high schools to universities is a bit uneven. Since high schools and their curricula are of widely varying quality, universities tend to pitch down in first year to accommodate the poorly prepared. (Did I just ring the Uncle Al bell? Yes, I think I did.) Much of first year was certainly review for me, to the credit of my high school and its teachers.

    I’m a bit surprised to hear AP credits haven’t solved this problem. Haven’t most of your physics majors taken AP Physics, and therefore could be sent directly to the second-year material?

    And as for the rest, would it not be possible to sort the incoming students into those who’ve never studied physics before, and those who have at least some background, and design courses accordingly?

  14. I ended up getting a minor in physics because my undergrad institution required me to take four courses in the division of the sciences outside of my major and I had no interest in labs that were wet, icky, smelled bad, or took a long time. Once I finished up the science requirement, I was pretty close to a physics minor. Plus, physics had no research papers!

    The advisor who helped me pick out courses my freshman fall was a physics professor. He told me that I didn’t need to take the first two intro courses since I had physics in high school, so I started in the class that went from special relativity through the beginnings of working with the Schrodinger equation (taught out of Tipler).

    I didn’t really like physics, but I was good at it, and the physics department was just so nice and really wanted me to take more physics classes (they kept trying to cook up ways for me to major in physics, maybe get a free masters degree in physics, etc. etc. etc.) that I felt like I had to at least finish out the minor.

    I suspect that the reason that I didn’t like physics is because I despise differential equations. 🙂

  15. Hmm, I think I finally parsed a possibility for what the CC in CCPhysicist means, given that my students match the description of his students.

    I very much wish I hadn’t been handed a list of requirements to teach, but the system apparently had a meeting a while back where all the full and part timers hashed out what was to be part of the curriculum. As an adjunct I have to hew to the party line much more closely than I’d like. Nonetheless, I told them two things on day 1: first, that they’d been lied to, since there is no such thing as “trig-based physics” (and sure enough, the arithmetic kills a lot of them, let alone the algebra). Second, I told them that I was planning to not to try to cram everything in the listed chapters and topics into their heads. It’s just not a realistic goal.

    Instead I’ve tried hard to focus on mechanics from a conservation law basis. I even kludged together a way for them to do an improved version of the PASCO “rotationa collisions” lab. (Dear god, what a stupid name. It should be labeled as being about angular momentum.) They struggle and struggle and struggle, but I keep pushing them, leading, cajoling, questioning, and standing there until they start answering questions and participating, all to emphasize the idea of conservation laws.

  16. re “just about any reform is good, as long as it doesn’t look like high school physics” — perhaps high school physics is a problem?

    re “the material is presented in a manner that’s much closer to the way practicing physicists think about physics.” and “The engineering departments run an intro class that’s based around projects and real problem-solving” — it may be that current teaching is too much a collection of facts and not meaning, values, and context.

    One of the greatest concepts of the PSSC physics and introductory physical science projects was that of a theme and a context. The problem I saw was that this did not meet ‘market expectations’. Those were for definitive content instruction, weekly tests with a 70% passing standard, and teacher as lecturer instruction mode.

    At the introductory level there is much to be said for an effective utilization of the history of the development of ideas, a clear theme of the course, and a solid plot line that connects course ideas together. In the small this is experiments and projects that follow a progression and build a context. In the large it is seeing how we know about the nature of light or the composition of matter.

    What physics education all too often becomes is a topical math class. The techniques become the focus and not the ideas and concepts. ‘Education’ becomes ‘training’ and skills get precedence over understanding. We get what we measure.

  17. (1) High School IS the problem. Of course I’m biased by having taken the big pay cut to go from teaching Science and Math in colleges and universities to teaching the same in high schools and middle schools. But correcting for bias, my wife published a paper (which her university particularly cited when they promoted her to Associate Professor, Physics) as a meta-analysis of what incoming college and university Physics students think that they know, but which is WRONG, due to incorrect high school Physics textbooks and/or bad high school Physics teachers.

    (2) My wife and I strongly agree: there should be Science Fiction in the curriculum for undergraduate Physics majors. If that doesn’t get them excited and motivated, albeit taking some effort to connect with valid science, then nothing will.

  18. I was a physics major in a college where nearly every other student was an engineering major. Almost everyone took physics, but there were very few in the major. In a class of 700 we had about 10 physics majors freshman year.

    I suffered from boredom in the intro physics classes and my grades took a nose-dive around final time in more than one class. Of the four physics classes that I took in my freshman year, the two that covered new (to me) material were the ones where I performed the best.
    I would most likely have benefited from an AP physics credit, but my HS wouldn’t offer it because I was the only student interested.
    When I got to sophomore level physics it was basically planned as a repeat of year one with added Diff Eq’s and Linear Algebra. I went running and screaming for the EE department halfway through the year. When my advisor suggested that I pursue a minor in physics I absolutely refused. I would have had very little work to do to finish a minor, but I wanted nothing to do with the department.

    All the interesting things I expected to find in the physics department were missing from my experience there. Engineering was new and interesting to me and I performed much better with respect to grades.

    Having to give up on my dream of being a physicist was heart-breaking to me. I still wish that I had stayed with it. I think that if I had studied at a University that implemented some of the suggestions given here I would be working in physics today.

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