A plug for rechargeable batteries

I am fortunate to have a reasonably well-stocked physics lab for my students. A number of the gizmos we use in the lab require batteries. Most of our battery-operated devices use the AA-cell.

A few years ago, I decided it would be worthwhile to invest in a lab set of rechargeable AA batteries.

Some people developed a distaste for rechargeables back in the 1970s when nickel-cadmium cells were used. Ni-cads had their issues, and they are disappearing from the rechargeable battery scene. They've been replaced by nickel metal hydride technology. NiMH batteries have enjoyed widespread adoption by digital camera users. They're good for hundreds of recharge cycles, and don't suffer the "memory" issues that NiCds were accused of having. They still check in with 1.2 volts (as opposed to the 1.5 volts of alkaline batteries), but I have yet to encounter that being a problem.

I use ten sets of four NiMH AAs and one eight-cell charger. The batteries and the charger get steady use throughout the year.

The current retail price of good rechargeable AAs is now less than $3 each ($10-$12 per set of four). Good alkalines run about $0.50 each. I'm happy with the performance of my NiMHs and I'm happy to not be filling the landfill with more and more discarded alkalines.

Buying advice? I've had good luck with Energizer and more recently Duracell. Look for high capacity values. As of this writing, I wouldn't go for anything less than 2500 mA h (milliamp-hours). Don't fall for fast recharge times--often that's how low-capacity batteries are marketed. Higher capacity batteries will serve longer between charges. And that's what's important.

Goodwin Liu... twenty years on

Physics teachers know everything. Or at least it seems that way when you're an interested student in a physics class. I recall feeling that way when I was such a student. I was also in the midst of deciding colleges and careers at the time. The only career path I consciously eliminated from the realm of possibilities was that of physics teacher. Funny how that turned out.

Part of being a physics teacher is revealing the workings of reality to students who have not yet been so enlightened. Mysteries are solved and misconceptions are dispelled. It's easy for a perception omniscience to accumulate around the wizard instructor. Some teachers revel in this perception and everything they can to perpetuate it.

I do not. I have some understanding as to the magnitude of my ignorance and rarely cease to be amazed by the immensity of my density. I've been lucky enough to have some truly brilliant students pass through my classroom on their way to greatness. I often tell friends and colleagues that I'm always delighted to get such students. "I get students that are ten times smarter than I'm ever gonna be," I tell them. That puts people a little off-balance. The teacher is supposed to be the smartest person in the room!

Of course, I'm a couple of pages ahead of them in the physics book, so I still manage to keep my bright students duly entertained and I've got things to teach them. But I can see that they've got capacities beyond my own. And that does not bother me in the least. I'm happy for them!

I was reminded of this when listening to National Public Radio the other day. It was a Nina Totenberg piece on the Supreme Court's ill-decided school desegregation case. Mara solicited analysis from UC Berkeley law professor Goodwin Liu. Goodwin Liu was a student in my AP Physics class my very first year of teaching. He went on to Stanford, Oxford, and Yale before returning to California as a professor at Boalt Hall. Oh, and he clerked for Supreme Court Associate Justice Ruth Bader Ginsberg along the way. Totenberg sought Liu's analysis because he's something of an expert in the area.

I sent him a note to tell him how proud I was. And he wrote back! Mind you, he's likely got somewhere between 1E+3 to 1E+6 better and more important things to than return an unsolicited note from a blast-from-the-past teacher. A teacher who was, erm, far from perfecting his craft that first year. What can I say? He's a classy guy in addition to being a learned scholar.

I also let him know that he will be giving me a personal tour of the Supreme Court once he's appointed. I'm nothing if not courteous in providing advance notice on such things.

Can you spot him in this archival photo?

Honor Mr. Wizard for fun and prizes

Rebecca Watson of skepchick.org is an energetic character known to all who attend JREF TAMs. And she is throwing down the gauntlet. Well, she's actually extending an invitation. She's more eloquent than I am, so I'll let her do the talking.Now get out there and get. Those. Projects!

California Capital Airshow '07

There's a certain energy, stress, angst, whatever associated with the end of the school year. Upon finalizing the check-out process, I'm typically overcome with an uncontrollable urge to go out and shoot something. With my camera, that is. Jeez, people!

Last year I spent some time in Sequoia/Kings Canyon National Parks. This year, I attended the California Capital Airshow. I had never shot an airshow before, so I stood to learn a thing or two.

I shot about 2000 frames with my trusty Canon EOS 10D digital SLR, most with my 100-400mm f/4L IS lens.

I winnowed that down to fewer than 200 keepers that I posted here.

I'm in the process of filtering that down to a smaller set that I'm willing to work on. The finished products are being posted here:
http://phyz.smugmug.com/gallery/3044261

Again, this is my first airshow shoot. So I make no claims about the composition, sharpness, or quality of the post-processing work. This is not where the poetic champions compose. But some of the finished images turned out OK.

I'm finished with the Thunderbirds and B-2 shots and am working backward through other aerial spectacles and static displays.

I've been AP-proved!

Shortly after my last post (blog-eons ago), I spent a day preparing the course syllabus for my AP Physics B course. Not for purposes of the actual course I've been teaching for over 20 years, but for the College Board's AP Course Audit.

Seems there's been too much ambiguity in what constitutes an Advanced Placement course as AP has grown more popular throughout the land (and around the world). The College Board felt the need to reign things in. So AP teachers were suddenly set upon with the burden of proving the worthiness of the courses they taught.

Yes, the very AP teachers who deliver college-level content to the best and brightest students, teachers who's "success" or "failure" can be seen in their students' pass rates, teachers who are--at some schools--asked to provide lesson plans to school administrators for purposes of documenting the fact that the portion of the school year following the AP exam will be spent doing academically rigorous coursework, those teachers had yet another task to perform.

And it was no trivial task. Rather it required extensive reading of background material and review of sample syllabi before beginning. Then it was off to matching your course to the College Board's expectations. I suppose if you were just starting a course, the process would be simpler. Just adopt one of the sample syllabi given.

For me, it was not so simple. I've crafted an AP course that was designed to work at my school for my students. I wasn't looking to scrap it and start from scratch.

Amusingly, the College Board recommends that AP Physics B should be a second-year course. But each of the example syllabi appeared to be AP Physics B as a first-year course. I suddenly discovered that my scheme of covering California academic content standards in my first-year non-AP course and covering everything else the College Board needs in my second-year AP course wasn't necessarily what this audit process was calling for. Suddenly the first-year AP Physics B course looked much more appealing.

The audit seemed to want every topic on the AP Physics B exam to be taught at the AP level. There appeared to be no benefit in having a first-year course to cover the basics and then a second-year course to build upon those basics. I was concerned, but I wasn't keen to scrap my two-year program. And again, other communications from the College Board openly promoted AP Physics as a second-year course. Having followed that recommendation suddenly put me in a bind for producing the kind of syllabus they wanted.

The sample syllabi were easy-breezy two- or three-page outlines. The monster I submitted was a nine-page tome. With small type.

I met the June 1st deadline for submission. Just. And I settled in for the promised two-month wait. Yesterday, I got the good-news email. The authorization is for Dean Baird's AP Physics B program at Rio Americano. If a new teacher comes along, they'll have to go through the audit. If I move to another school, I'll have to go through the audit again.

Which constants should students memorize?

High school physics students, specifically.

Some might argue for none. I can see some reason in that. Many think of memorization of any kind as a burdensome task that kills all joy for miles around. Such absolute aversion may be an overreaction to bad instructional experiences from one's own past.

At the moment, I can see some value in having high school physics students internalize five constants:

Gravitational acceleration at the surface of the earth: g = 9.8 m/s^2
Elementary charge: e = 1.6 x 10^-19 C
Speed of light in free space: c = 3 x 10^8 m/s
Universal gravitation constant: G = 6.67 x 10^-11 kg m^2/kg^2
Coulomb constant: k = 9 x 10^9 N m^2/C^2

High school physics teachers all tend to think alike and readily agree on all maters pedagogical. So I'm guessing that if these are the values I think should be memorized, the rest of you agree by default. Am I right?

Why the sky is blue

Here is my lesson on why the sky is blue. It's a combination "springboard"/presentation. That means students get a sheet with questions to be answered through class discussion during the presentation. The presentation includes images and animations to illustrate what's going on. Read over the student worksheet (and especially the teacher's edition with answers) and step through the interactive presentation before trying this one in class. This is no autopilot-style lesson. The teacher must teach this one and you need to know some details to flesh the whole thing out.

Student Springboard (worksheet)
Teacher's Edition (answer key)
Presentation (zipped interactive QuickTime: 39MB)

LESSON REQUIREMENTS
QuickTime (free)
Means to project the presentation (not free)
Resonant tuning forks
PTSOS visible optics "skinny fish" tank
Scattering agent (Mop-N-Glo or equivalent)
Flashlight (mini maglite or equivalent)

As always, I'm eager to hear your comments.

What's up with PhysicsBowl 2007?

I ask because I've been checking the official unofficial website at

http://phys.udallas.edu/AAPT/

and I'm not getting this year's results. I can see this year's test and answers, but not the results of the competition. If you know something I don't let me know.

You know what would be good in a situation like this? An online physics educator forum (see the post below).

UPDATE 1: Wednesday has come and gone; still no results. I posted a query to Richard Olenick, current head honcho/fearless leader of the AAPT Examinations Editorial Board; I'll let you know if I hear anything. In the meantime, it's fun to watch the page counter spin. When I started checking the page mentioned above, the counter was under 6000. At the moment of this update, it's pushing 9000. Yeah, I need to get out more.

UPDATE 2: The results are in. The Division 2 average was 17 out of 40 (typical of this challenging competition exam). In the California/Hawaii Region, first place went to Mission San Jose in Fremont, CA. Second place went to Mira Loma right here in Sacramento! The top scoring student in our Region/Division was Henry Tung of Torrey Pines in Santee, CA. Second place student was Erik Chen of Mira Loma! Congratulations to this year's winners. For complete results, click the link posted above.

Listservs are sooo 1995

Ah, institutional inertia. We physics educators might pride ourselves in innovative techniques and strategies, but in the end, we're likely as bad as anyone else.

So it is with listservs. When email was an emerging technology, the listserv provided a means by which people with similar interests could broadcast emails to each other. Responses were similarly broadcast, and conversations took place. Listservs were good. At least they were in 1995. The physics teaching community weighed in strong with the Physhare and Phys-L listservs, not to mention the AP Physics listserv.

Time and technology march on, though. So these days, people with similar interests typically communicate via online forums. These are webpages that fill with threads comments from individuals. Not strings of email to clutter up your email storage space. Webpages that occupy their own webspace. Brilliant! And de rigeur for online communities since about 2000.

Examples: The DPReview Forum (for digital camera enthusiasts) and the JREF Forum (for skeptics).

So here it is 2007. Physhare and Phys-L continue apace. But where are the true online fora for physics educators? If I had the skills, I'd set one up myself. Clearly, there are physics educators out there with the skills. It takes time, talent, and energy just to keep the listservs afloat. But listservs are yesteryear's news. Reminds me of ye olde BBSs: great in their day, but their day has passed.

If they're out there and I'm too dim a bulb to find them, please light my way! And if you can tell me why a listserv is better than a true online forum, please do. I'm clearly ranting here, but I'm open to education.

Science PhD gender gap narrowing?

It could be that I lack the proper optimism, but the trend didn't appear as earth-shattering to me as it did to the author of the article. Especially the most recent data points! When the top bar on the graph is at 50%, I'll breathe a little easier. Until then, there is work to be done. Click the graph to get the full story from the Sacramento Bee.

Among the best lines from the article: "[Suzanne} Barber, a fourth-year doctoral student, is one engineer who hopes the phenomenon leads teenage girls to discover the sciences and reject frivolous media portrayals of young women. 'This idea -- be like Paris Hilton or Mandy Moore. I think it's important to show a different side of what a woman can be,' said Barber, who is studying materials science engineering.


Bonus blogpoints if you can identify what's wrong with the graph. Comment away!