Archive for the 'Science Education & Outreach' category

More thoughts about teaching on the block system

So, yes, it's been nearly two months since my last post, and posts were few and far between even then. Well, right now I'm on winter break (and have been for almost a week), and I'm back into a state of mind where I can post. There may be a torrent of them in the next several days; we shall see.

A few months ago, as I was just getting started here at Quest University, I posted about teaching on the block. The block system is how classes are organized here, in the same way as Colorado College. Students take one class at a time, and hyperfocus on it. That also means that I'm teaching one class at a time, but cram a full semester's worth of teaching into 18 extremely intense days. When I'm teaching on the block, I can do almost nothing else. It really does take away your focus. It's not just the hours. Yes, because I try to be available to my students, many days I'm spending several hours talking to students in my office outside of the three "contact" hours in class. (There are also students who aren't in my class, but with whom I talk, either just because they drop by, or because I'm taking them on as a mentor for their last two years, or because they want to talk about future classes and independent studies.) However, it's also the "energy" level. I put energy in scare quotes, because of course it's not something that's measured in Joules and that would be recognizable as energy to a physicist, but it's the sort of "energy" that we mean when we tell each other that we're feeling particularly low energy today. There's only so much creativity and intellectual effort that one can put into something until one is exhausted, until the point of diminishing returns is indistinguishable from its asymptote. (This is why the notion that grad students are supposed to work 80 or 100 hours a week, and the schedule that medical residents or programmers on a "death march" are put on, are fundamentally absurd.)

I'm learning other things about teaching on the block— things that, to be fair, I was told about ahead of time. The most important lesson is probably "less is more". This is true of teaching in general. When I first started at Vanderbilt, there were seminars about teaching for the new faculty where they basically told us this. (Faculty would say that every time they taught the same class again, they'd try to cover less than the previous time.) This is even more true on the block. The format just does not lend itself to "survey" classes (of which I have to admit that I'm dubious anyway!). Because you're working closely with students for three hours, probably three consecutive hours, each day, it's far more suited to getting into stuff in depth than it is to driving by a large number of topics.

This last block, I taught a first course in calculus-based physics. I used Thomas Moore's books Six Ideas That Shaped Physics. I'm finding that (with one or two caveats) I like these a lot. There are six books. At Pomona, he uses three each semester. Each chapter is designed to go with a single 50-minute lecture period. Already, you can see that I have to adapt a little. I find, however, that three chapters is far too much for a single 3-hour class meeting. Thomas Moore goes through three books a semester, and I'm doing the same thing right now: three books in December, three books in January. However, next time I teach this, I think I'm only going to use two books each course. That does make me a little sad, as the third book from Physics I is Relativity, and I think it's very cool that if students only take one calculus-based physics course, they get some Special Relativity. (I also really like the way he does Relativity, emphasizing the metric (or the "invariant interval"), and getting to that before the "cool effects" of time dilation, simultaneity, and length contraction.) However, my observation is that we rushed through the material too fast, and that students didn't digest the material as well as I had hoped. On many things, I wished we had a second day to work through problems and work with the things we were working on. So, in the future, I'll do Conservation Laws and Newtonian Mechanics in the first physics course; Relativity and Electromagnetism in the second; and save Quantum Physics and Thermodynamics for the third. (That will be two years from now; Quest isn't big enough at the moment to teach introductory calculus-based physics every year.)

As time goes by, I hope to find a way to keep up with blogging while teaching on the block. However, if I'm slow to post, it's almost certainly because teaching on the block really does take over your life. It may only be during the summer, or during blocks I'm not teaching (which at the moment appear to be being taken over by planned independent studies!) that I will be able to keep up with blogging!

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Why P=nkT is better than PV=NRT

If you've ever taken a Chemistry course, you've run across PV=NRT. That is, of course, the ideal gas law. Real gasses approximate ideal gasses; the noble gasses (Helium, Neon, Argon, Krypton, Xenon) probably approximate it best. It tells you that the pressure times the volume of a gas is equal to the number of moles of that gas, times the ideal gas constant, times the temperature in Kelvins.

So, fine. It's useful, and I've used it a lot. My problem is that as a physicist, I think that moles are an extremely gratuitous unit. Sure, I recognize that you're more likely to be dealing with 32 grams of O2 than 32 individual molecules, but still, it's yet one more concept that doesn't do much for me. What's more, the ideal gas constant is a constant that, at least as its name suggests, is of limited utility.

I much prefer this formulation:

P = n k T

All of the same information is there. However, instead of the ideal gas constant, we've got Boltzmann's Constant, which is a much more fundamental constant. Yes, all the same information is there— except that it doesn't come in units containing moles, so you don't need to know the definition of moles to use it— and Boltzmann's constant shows up as is in a lot of other equations.

On the left, we have pressure, the same as before. On the right, we have the number density of the gas. The variable n, instead of being just a number, is the number of particles per volume. OK, I will admit, that's going to tend to be a huge number. If I did my calculations right, for a gas at room temperature it's going to be something like 3×1025 m-3. So, I will admit that that is one advantage of the chemist's way of formulating it: the numbers are easier to deal with.

The rest of the right is kT. What's neat about that is that if you do physics (and probably chemistry as well, and probably many other natural sciences), you're used to seeing kT all the time. Boltzmann's constant times the temperature times a number of order 1 is the average kinetic energy of a particle in a gas that's at temperature T. This (other than aethetically preferring k to R) is the primary reason I prefer this formulation of the ideal gas law. It's got a piece in it that lets you directly connect this to other physics. "Aha", you say, "this law is somehow related to the average energy of individual particles!" And, sure enough, if you realize that pressure is the rate at which particles are crossing an imaginary wall, times the amount of momentum that each particle carries with it across that imaginary wall, you realize that it should be related to the kinetic energy of that particle.

There's another thing here. If you look at "nkT", you'll realize that that is just a number of order 1 times the kinetic energy density of the gas. kT is (close to) the kinetic energy of each particle, and n is the number of particles per cubic meter (or per cubic centimeter, if you like cgs units better). This leads immediately to the realization that the units of pressure are exactly the same as the units of energy density— something that seemed perverse to me the first time I came across the stress-energy tensor of relativity, as I'd been brainwashed into thinking they were entirely different things by the obscuration inherent in PV=NRT. To be sure, pressure and energy density aren't the same thing, but they are related. (One could say that energy density is momentum flux in a temporal direction, and pressure is mometum flux in a spatial direction, but you need an appreciation of spacetime for that to be illuminating.)

It may be just me as a curmudgeonly physicist talking back to chemists who've figured out a more convenient way to deal with it. I've certainly come across curmudgeonly physicists who express disbelief and either horror or amused condescension that astronomers would use a unit so silly as the "Astronomical Unit"... and their reaction is simply the result of them not being used to it, and not realizing that that unit is extremely convenient for star systems, just like their fermi is extremely useful for atomic nuclei. However, I do really think that from a clarity of concept point of view, P=nkT is a much better way to state the ideal gas law than PV=NRT.

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Do science students do their reading?

Many science professors hold it as an article of faith that students do far less of the reading in their classes than they do in humanities and social science classes. I heard this expectation expressed at the APS workshop for new faculty I went to several years ago, and in other presentations I've heard about physics and astronomy education. The technique Just In Time Teaching was invented partly as a way of allowing science classes to make better use of textbook reading. Is it not a waste to spend classroom time in information transmission, telling students in a linear fashion what they could just have easily read from the textbook? Physics education research has shown that active learning is much more effective in getting the students to really understand the concepts.

When I've heard talks about this, the view I've heard expressed is that it would be crazy to expect students to come to a literature class without having done the reading. They would be completely unable to participate in that day's discussion. On the other hand, the view is, the norm is that students don't do the reading for their physical science classes, except perhaps in a last-ditch attempt to figure out how to do homework problems ("find an example that matches!").

In my statistics class that met this last September (ending last Friday), all of the students had a project; they chose a question, obtained data, and analyzed it. One student, Julian Seeman-Sterling, surveyed students at Quest to find out how much of the reading they did. Below are a couple of his results:

Histogram about Reading

You can tell just looking at the histograms that there's no appreciable difference between the amount of reading that students claim to complete in the natural sciences as compared to other disciplines. And, indeed, Julian ran a statistical test on these, and there's no evidence of any difference. (Note that Julian calls "physical science" what is more commonly called "natural science"— that is, it includes things such as biology.)

I do have to say that I was surprised to hear that, but of course it all comes with caveats. These are the results of a survey of students at Quest. Quest is an unusual place; students only take one class at a time, and it's very intensive. They don't have stacks of reading for many different classes to do; they only have the one class. As such, they tend to be very engaged with the one class they are taking. Also, these are the results as reported on the survey. As Julian pointed out during his presentation in class, he couldn't know if they're really true without following a lot of students around throughout their day... and that wouldn't be entirely practical.

So, do students do less of their reading in physics and astronomy than they do in their humanities courses? I don't know. Julian's data suggests that that is not the case at least at Quest.

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Teaching on the block

As you will know if you've read the sidebar of this blog, I teach at Quest University Canada. I've started there this year, and started teaching my first class just under two weeks ago. The class is "The Practice of Statistics". Because Quest is so small, the faculty here teach a wider range of subjects than they would elsewhere. At Vanderbilt, I taught only astronomy (with undergraduate General Relativity having been defined as an "A" course so that students could count it towards an astronomy minor without our having to revise the catalog description of the minor). At Quest, the first class I'm teaching is a math class.

Quest runs on the "block system". This is a system for scheduling courses that was pioneered (I believe) at Colorado College; certainly CC is the best known college that's on the block system. Students take only one class at a time. However, they hyperfocus on the class. Class meets three hours a day, every Monday through Friday, for three and a half weeks. Then there's a two-day block break (next to a weekend, so it's sort of a four day weekend), and the next block begins. Full-time students take eight blocks over the course of two semesters, so it amounts to the same number of courses. (You aren't really able to overload, however.)

Professors teach six blocks during the year. This is also a similar load; at the higher-end private liberal arts colleges, the typical teaching load (I hate that term, but that's a rant for another time) is either three courses a semester, or two one semester and three the next. (Lots of details about lab courses complicate this.) (This is in contrast to a research University, where scientists might only teach one course a semester.) However, if you think about it, at a typical college those six courses are spread out over eight months. On the block system, those eight courses are condensed into less than six months. Everybody who has taught on this system has told me, and I can now confirm this from my limited experience, that the course you are teaching takes over your life, and you can do basically nothing else while you are teaching.

Each day, I teach from nine to noon. I usually decompress a bit, and then spend the afternoon trying to get some grading done, but in practice I spend a lot of the time talking to students. In the evening, I complete whatever grading there is to do, and then try to figure out what we're going to do in class the next day. Then I collapse, go to sleep, and start over the next morning.

Because students are there for three hours straight— we do take a break in the middle, but that's it— you can't approach the class the same way you would if you saw them for an hour three times a week. Straight lecturing just doesn't make sense; you can't just talk at people for three hours straight. Or, rather, you can, but you will probably dull their minds permanently. Of course, astronomy and physics research has shown that straight lecturing basically doesn't work anyway, so that's just as well! In statistics, I talk at them a little bit, but try not to talk at them uninterrupted for more than 10 minutes or so in a go. We spend a lot of time working through processing data (using GNU R), there are "labs" that the students do in small groups, and I'll sometimes give them problems and challenges to work out individually during class.

So far, I like it. Yes, I'm pretty damn busy, but I knew that that was going to happen going in to it. I like the fact that the students are hyperfocusing on my class. There's no other classes whose tests and homework compete with mine. They aren't going to neglect my class because another has a big project due. Their attention isn't divided. I don't know if this is the best way to do things for all students, but when it comes to how I, personally, have learned things throughout my life, it's very unnatural for me to try to learn several things at once and spread it out over several months. If I'm learning (say) a new computer language for a project I need, I will dig into it and focus primarily on that for a long time. It means less multitasking. Generally, when people talk about multitasking, they're talking about switching tasks several times a minute or an hour, but switching tasks a few times a day is also a form of multitasking, and it can also be distracting.

This year, after the statistics class, I'll be teaching a class that's part of the foundation courses entitled "Energy & Matter". After that is an astronomy course, and then two courses in a sequence of calculus-based physics. That will have been five blocks in a row, each with a different course, so I expect when it's over and February rolls around, I'm going to be completely used up. I plan to get nothing done in February; I am just going to recover. In March, I teach "Energy & Matter" again, and then the year is over for me. One of the advantages of having your teaching condensed into six months is that in the other months, you may actually be able to focus on other things and get a real amount of research or development done. I'll see how that goes this coming April! (And maybe in February, but I really do expect I'm going to need to decompress.)

I will have a lot more to say about what it's like to teach at Quest as time goes on.

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NPR's Science Friday with a (Second) Live Studio Audience

If you listened to Science Friday on NPR's Talk of the Nation today, you may have heard Ira Flatow mention a question from "Prospero Linden"— that was me. I was there, live, along with a 30 or 40 other people in the studio audience:


For the last several weeks, Science Friday has been simulcasting over NPR and in Second Life, using Nashville's WPLN audio stream for the purpose. (I had nothing to do with that!) Meanwhile, Ira Flatley, the 2nd life avatar of Ira Flatow (and his extensive staff), together with hosts, listen to and repeat on air the occasional question that comes from the sundry people present. Meanwhile, all of us carry on a text conversation about what we're hearing on the radio, sometimes with various tangents.

If you're interested in this drop by next week. Science Friday is hosted in the Science School region in Second Life.

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Book review : Storm World by Chris Mooney

Read this book.

First and formost for a book review: Storm World is a good
read. You will not find yourself bogged down or forcing yourself to
push through a book that's "good for you." You will keep reading
because you will want to know more.

As for the book itself: Mooney clearly has a point of view in the
book, and does not hide it. However, that point of view is considered
based on the evidence, and he also admits that it is not exactly the
same as the point of view he expected to have when starting research for
the book. This is not a polemic, it is not a "the sky is falling, we're
all gonna die!" rant about hurricans and global warming. Even if you
are one who is inclined to doubt all of that, I strongly encourge you to
consider reading this book.

The book is really about two things. First, it's a historical and
present account of our increasing understanding of just what hurricanes
are, including that there still is a lot about them that we don't
understand. Second, it's an examination of the scientific process which
is in many ways more honest and true to reality than many of the
sugar-coated versions of the scientific process that we hear.

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Accelerating Universe Talk Transcript & Followup

I managed to get through my 15-20 minute "talk," and just as I threw it open for questions Second Life had a database problem and everbody in-world had to be logged out.... We got back in 40 minutes or so later, and I answered questions for a while for people who came back. However, if you were at the talk and wanted to ask questions but didn't come back, I'll be doing a follow-up Q&A session tomorrow (Wednesday August 1) at 10AM PDT at the same location.

Below, I've got a transcript of the talk I gave. Other than fixing some typos and merging things into paragraphs, I haven't edited what I said/typed.

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A cynical take on a study about high school science

Jul 27 2007 Published by under Science Education & Outreach

Chad links to an article about a study that shows that good preparation in high school math helps students perform in all science disciplines in college, whereas studying one science in high school doesn't help their performance in other science disciplines in college.

There are a few conclusions that are drawn. The article quotes people who suggest that the "Physics First" movement— that argues Physics should be taught first, with biology and chemistry later— doesn't hold water. Chad resonates with the article, having observed that college students often have woeful preparation in math, and that this disadvantage cripples them and prevents them from moving on.

Let me propose another, cynical interpretation.

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Undergraduate research : a key (essential?) component of a college science education

Apr 30 2007 Published by under Science Education & Outreach

Following Chad and Jake, I want to jump off from an article in Science about undergraduate research. It's always nice when some sort of survey confirms one's preexisting biases....

In short, the survey found that performing research increased undergraduates' interest in science and technology fields (so-annoyingly-called "STEM" disciplines, for Science Technology Engineering Mathematics). Such undergraduates were also more likely to go on to advanced degrees, although here the causality isn't necessarily clear. The survey did find that students with higher grades tended to be more likely to get involved in research; this raises at least the possibility that "getting involved in research" and "going on to an advanced degree" are affected by a common cause, and that the former doesn't necessarily increase the probability of the latter.

Of great importance was the fact that undergraduate research seemed to improve the confidence and future success of underrepresented minorities and women. I'm not sure I can tell you what is particularly "white male patriarchy" about classroom performance, but if this is a way to help people realize their true abilities in science regardless of their ethnic background, then it could be an important component in the continuing problem of minorities and women in science. (Indeed, the title of the Science article is "The Pipeline: Benefits of Undergraduate Research Experiences.")

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