Monday, January 29, 2007

Post-PTSOS2 note: Leidenball video clips

This is the clip I showed of the very hot brass ball immersed in 75degC water. The envelope of water vapor around the ball is the result of the Leidenfrost effect. The poor thermal conductivity of the vapor allows the ball to remain hot for a surprisingly long time.

I shot this one in class with a highly vocal and somewhat roudy group of Advanced Placement Physics students. I didn't tell them what was going to happen beforehand, but you can hear one of them say, "Leidenfrost, eat your heart out." They had seen Jearl Walker's Leidenfrost effect video one calendar year earlier.

While trying to film the effect, I ran through several takes. Not all of them went according to plan.

Still, there's a lesson to be had here. How is it that the ball could sit in the flame for ten minutes only liberate itself from the rod stem seconds after being immersed in the water?

Here's the one I shot of demo discoverer, Paul Robinson, showing the Leidenball at the workshop.

Technical note to Mac OS X users hoping to upload clips to YouTube. If you upload QuickTime files to YouTube, the sound will lag behind the video by a second or two. Be sure to convert your clips to MP4 format for uploading to YouTube. Apple's QuickTime Pro ($29) will do this.

Sunday, January 28, 2007

Post-PTSOS2 note: Book of Phyz resources

At the workshop, I gave out copies of curriculum materials from The Book of Phyz. There are additional resources on the topics we covered available online. Additional items include informational handouts, classwork and homework assignments, video question sheets, crossword puzzles, practice tests, and presentations (in QuickTime format). The resource pages are works in progress, and there may be some broken links and resources not yet posted. But at least the price is right.

Book of Phyz: Introduction to Heat (Physics 1)
Book of Phyz: Advanced Heat and Thermodynamlcs (AP Physics 2)
Book of Phyz: Waves (Physics 1)
Book of Phyz: Harmonic Motion and Resonance (AP Physics 2)

Some attendees hoped to see dynamic demonstrations or labs involving heat engines. To this I say: "Me, too!" In my limited experience, the topics of thermodynamics simply don't lend themselves to flashy demos or engaging labs. And please read that as an invitation to educate me in the comments. Sure, the fire piston is flashy (literally), but it won't help much on an AP heat engine question.

In the meantime, I would suggest visiting the Advanced Heat and Thermodynamics page and downloading the PhyzJobs relating to thermo. The Springboards on The First Law, PV Processes, and PV Cycles are designed to take students gently into the realm of PV diagrams and heat engines.

Post-PTSOS2 note: commercial resources

During the workshop, I made heavy use of Pasco's WavePort software to work with sound waves. With WavePort, students can manipulate a sound wave, manipulate interfering sound waves to create beats, analyze sound waves input to the computer via built-in or auxilary microphones. A classroom license currently costs $159. I find WavePort to be of great value in the physics lab; I would hate to teach waves without it. There may be programs that do similar things out there. If you know of any, please add the info in the comments.
Pasco's WavePort Home:

(By the way, a disappointment was expressed in that we showed WavePort, but didn't give it away. The good news is that the page listed above links to a free, downloadable 30-day trial of WavePort.)

I also showed a clip from the somewhat encyclopedic video clip resource, Physics: Cinema Classics. P:CC is an excellent resource and inspiration for demonstrations. I don't use every single clip on P:CC, but the ones I do use aren't available elsewhere, and I would have a hard time trying to reproduce them on my own. I would hate to be without P:CC. You can buy P:CC from Ztek for $999. Members of AAPT can buy it through AAPT for $799.
Ztek's Physics: Cinema Classics Page:
AAPT members get a discount!

(A question was raised as to whether P:CC was captioned for the benefit of the hearing-impaired. After reviewing the online information about P:CC, I have to conclude that it is not captioned. If it is, Ztek appears to be keeping it a secret.)

I showed a demonstration of the Galilean thermoscope. The demo requires a long-necked, small-bulbed Florence flask. Current price: $8.55.
Air Thermometer (Galilean Thermoscope) Page:

Was there any other commercial resource we alluded to on Saturday that I should link to? Let me know in the comments.

Post-PTSOS2 notes explained

Physics Teacher SOS (PTSOS) is a new teacher mentoring project I've been involved with since its inception a few years ago. The program is a collaboration of Paul Robinson (San Mateo High School), Stephanie Finander (Woodside High School), and me. We are assisted by the likes of Clarence Bakken (Gunn High School, retired), Dan Burns (Los Gatos High School), and a crew of physics teaching "veterans."

We run a series of three New Teacher Workshops each academic year. This past Saturday, we ran our second workshop. The principal topics were heat, waves, and sound. Based on the feedback forms filled out by participants as well as my own hindsight, I will offer a few post-PTSOS2 notes.

I should note that PTSOS is a project of the Northern California and Nevada Section of The American Association of Physics Teachers and is sponsored by The Karl L. Brown Memorial Scholarship Fund.

Wednesday, January 24, 2007

Tips on posting grades and related issues

There are two things parents typically want to know about their child's situation in your class. One is how the child is doing (the grade in progress) and the other is what the child can do to improve his or her standing in the course.

I think they're entitled to good answers on both issues. And I do my best to provide as much.

The homepage of my website (, I have a link to the latest grades in progress. The grades document is a PDF "print" of the same grades I post in the window of my classroom. They are listed by period and coded by student phone numbers. Parents can access this information wherever they have access to the Internet.

During the semester, the grade information is provided in great detail. Speciifc test scores and lab scores and various percentages, etc.

But at the end of the semester, I list only the letter grade. This avoids the errant conversations that typically arise from percentage values that end in a 9. While the vast majority of students and parents understand how grades are given, a few do not. A student with a 79% will feel entitled to a B. Why? Because they were so close! No other reason is necessary. Again, these are few and far between. But not nonexistent.

Anyway, I also keep a list of suggestions for students who wish to improve their performance in the course. It can be found--in PDF format--here.

TAM Mania!

So much to say about The Amaz!ng Meeting 5, and me with so little eloquence. Fortunately John Rennie, Editor of Scientific American, has a wonderful description and review right here.

One unexpected highlight was watching James Randi go live on Anderson Cooper 360 to provide an accurate description of Sylvia Browne and her kind. Most poignant: Anderson Cooper refering to Browne as an "alleged psychic." The one-two punch of Randi and fellow skeptic (and TAM attendee) Robert S. Lancaster brought joy to the heart. The conference room filled wih TAM attendees was the place to watch this event; it included substantial audience "participation."

Here's the clip:

I'll never be able to post all I'd like to about TAM5. The TAM entry below has a link to an attempt some of us made to blog from TAM. Looks we got too distracted to do it well.

Wednesday, January 17, 2007

CST RTQ orange alert!

It appears that there have been some "issues" in bringing the Released Test Questions out to the public this year. Hence the delay. I'm assured they are aware of the problem and working toward a solution. The latest is that they expect the RTQs to be up by the end of the month.

So don't go to the site below and hit your refresh button in anticipation (i.e., don't hold your breath).

If February arrives with no RTQs, I say we start manufacturing criticism not based on actual items at all. Sharpens the skills.

Off to The Amazing Meeting

I fly to Las Vegas today. TAM5 starts tomorrow with the teacher workshop, and continues Friday and Saturday with the invited talks. It concludes Sunday with the contributed talks.

I've signed on to help out with a TAM5 blog. I have no idea what type of content is going to show up there. Some of it may be PG-13 (I'm thinking of the unofficial events-related commentary).

The TAM5 blog is here. I've already contributed my first post.

Friday, January 12, 2007

Magnetic Mecca Madness

Oh, the things magnets can do. I wonder if there is anything that they can't do. Crackpots never stop inventing new uses for "medicinal magnetism." People have an innate fascination and thorough lack of understanding of magnetism. So it should be of little wonder that magnetism is hijacked for all sorts of woo shenanigans.

But my colleague, Darren, sent me this gem from Little Green Footballs, and I confess it was news to me. And by "news," I mean "complete hogwash." But don't take my word for it. See for yourself.

Why switching from Greenwich to Mecca will put things right with Mean Time and Life in general.

Maybe it's just a bad translation. But I doubt it.

Friday, January 05, 2007

OT: You can take the boy out of the midwest...

Twenty years in California and I can't shake my Grand Rapids linguistic upbringing. Hey, I got a personalized license plate, I eat guacamole, I snow-skied one day and sunned myself on the beach the next. And I call it "soda!" What do you want from me?

What American accent do you have?
Your Result: The Inland North

You may think you speak "Standard English straight out of the dictionary" but when you step away from the Great Lakes you get asked annoying questions like "Are you from Wisconsin?" or "Are you from Chicago?" Chances are you call carbonated drinks "pop."

The Midland
The Northeast
The South
The West
North Central
What American accent do you have?
Quiz Created on GoToQuiz

Thursday, January 04, 2007

C'est la morte

Le contestant d'exposition de jeu est défié une fois demandé quel objet satellise la terre. L'assistance n'aide pas.

I'm not sure if that made any sense.

I am sure that this does not. It shows a clip from the French version of "Who Wants to Be a Millionaire?" The question is "What revolves around the Earth?" the choices are A. The Moon, B. The Sun, C. Mars, or D. Venus.

We should take no joy from watching a game-show contestant squirm under the weight of a question that is clearly difficult to the general public. But I guess this is like witnessing a sibling getting disciplined. Instead of a graphic, anecdotal indictment of the US educational system, this clip slams the French.

Watch carefully at 1:27 as the host betrays a touch of frustration with the results of the audience poll.

Aristotle and Ptolemy live on! Thanks to The Amazing Randi for the link.