A Goldilocks analysis of the Physics RTQs

Each year since 2003, the California Department of Education has released 15 questions from the physics CST (California Standards Test). The growing collection is known as the Physics RTQs (Released Test Questions). One RTQ was removed from the set for bad behavior. It deserved it. So as of 2009, we have 89 physics RTQs.

There are 45 content standards in California's 9-12 Physics. How well do the RTQs cover the standards?

One might think that once the number of RTQs reached 45 (in 2006), all the content standards would have been covered. But the reality of selecting RTQs is not so simple. The process is necessarily complex. As a result, some standards were represented with multiple RTQs while others went uncovered. (Remember, too, that the Investigation and Experimentation Standard Set must also be represented in the RTQs.)

As of this year's RTQ set--including items from the 2008 test--all 45 physics content standards are covered.

One hopes that future RTQ releases will fortify weakly-represented standards and increase the variety of item types in the set.

There are many things one can do when not burdened with spouse or children. I will not burden this post with an exhaustive list. But one task that falls under the aegis is my thorough

Physics RTQ Distribution Analysis PDF XLS.

This gem is a spreadsheet listing all the RTQ items by year of release and (more importantly) by standard. The actual items are in the RTQ PDF from the CDE; the spreadsheet merely shows their distribution. Go ahead, click and open it. I dare ya! (PDF or Excel.)

This representation makes it easy to perform a Goldilocks analysis of the RTQs. That is, you can see which standards are over-represented, which ones are under-represented, and which ones are represented just right.

You really should open it and marvel at the OCD that was required to prepare it. And, of course, thank your lucky stars that you do not suffer such a level. But for the faint-of-anal-retention, I offer this:

2009 Executive Summary of the Physics RTQ Distribution
1. All Standard Sets are represented in proportion to the test blueprint.

2. Most individual standards are represented in balanced proportion.

3. The following individual standards are over-represented in the RTQs. Future RTQs sets should be selected in a manner that will exclude new items from Standards
1.A, 1.B, 1.G, 2.A, 3.C, 4.C, and 5.B.

4. The following individual standards are under-represented in the RTQs. Future RTQs sets should be selected in a manner that will include new items from these standards.
a. Primary needs lie in Standards 2.F, 4.F, 5.D, 5.E, 5.F.
b. Secondary needs lie in Standards 2.E, 3.B, 3.E, 4.A, 4.D, 4.E, 5.H.

For those who haven't memorized the standards by their alphanumerical designations, a truck will be around later to bring you to re-education camp. In the meantime, you can check the Blueprint. Spoiler alert: Set 1 is Motion and Forces, 2 is Conservation of Energy and Momentum, 3 is Heat and Thermodynamics, 4 is Waves, and 5 is Electric and Magnetic Phenomena. See the blueprint for the letters.

Milk carton storage box

Whether times are lean or not, this storage box is a good idea. Handy, simple, and sturdy; these boxes are answers waiting for your small-item storage questions.

For those who like instructions, here are the instructions!

Do not Mach fast kitteh

see more Lolcats and funny pictures

Dart guns... They're back!

I recently added a version of my Newtonian Dart demo to the upcoming Conceptual Physical Science Explorations 2e Lab Manual.

The trouble is getting good dart guns for this demo. When those of us "of a certain age" were young, these toys were easy to find in drug stores, grocery stores, and--dare I say--the five and dime! You need the classic, hard-stick and suction cup, spring-loaded dart guns.

But somewhere, this type of dart gun was used in a manner inconsistent with its intent. So it was pulled and replaced with safer versions. Bendy, flexi-rubber darts or foam darts were flung by a mechanism that didn't allow for downward firing. And so they were useless for a great demo for showing Newton's second law.

Arbor Scientific has risen to the challenge and found a batch of these classics. I hope they can find a supply steady enough to keep me stocked when mine expire.

Southern California Physics Teachers Spring Meeting

SCAAPT Spring Meeting
Saturday, May 2
CSU Channel Islands

Bobbing for magnets, take 2

Here's my second attempt at a groovy electromagnetic interaction demonstration. It's based on a setup I saw Don Walters use at The Naval Postgraduate School at an NCNAAPT meeting. He did a quick take, and I thought it was an improvement on The Exploratorium's Magnetic Pendulums.

As I often do, I milked this demo (and many tangents to it) for all I thought they were worth. To summarize, this demo shows electromagnetic interaction and slowly and carefully constructs observational evidence for Lenz's law.

Find the PDF here: Bobbing for Magnets PDF.

Find the answer key PDF here: Bobbing for Magnets Key PDF.

Find the preso here: Bobbing for Magnets QT. My presentations are rarely simple, linear expositions of the corresponding worksheet. You've been warned.

UPDATE: Fixed the link to the PDF. (Thanks Alby and Stephanie.) AND, I added a QuickTime Presentation for your enjoyment.

Skinny Fish Tank media

The Skinny Fish Tank has now been unleashed to the world, thanks to Arbor Scientific. They call it the Laser Viewing Tank (P2-7690), but it's still a skinny fish tank to me. It's very low tech and doesn't seem worth very useful until you see it in action.

Even though I know how groovy it is, I'm still amused by the enthusiasm I see in colleagues when they see it in operation.

Here's a photo album I made for Arbor using a prototype (that had seen years of classroom use).

And here's Arbor's product description video. Don't you wish all science suppliers made videos of their products in action? Arbor's created dozens of these things and is always making more. Let's hope other companies follow Arbor's lead.

PhET postings

As mentioned in previous posts, I'm a big fan of the PhET simulations.

Today, I posted three activities to PhET's teacher-sharing resource. These are PDFs of student pages and notes for classroom activities/virtual labs.

"Worlds of Wonder" can be found at PhET's "My Solar System" simulation description page. First you simulate Newton's Cannon; eventually you find the relationship between orbital radius and orbital speed.

"Quest for the Coulomb Cup" can be found as PhET's "Electric Field Hockey" simulation page. I tried to recreate the student activity I originally wrote to accompany the old, original Ruth Chabay/Academic Software simulation that I can no longer run. This one remains a student favorite.

"Water Waves in an Electric Sink" can be found at PhET's "Wave Interference" simulation page. It allows exploration of the effects of changing the amplitude or frequency of a wave source.

Imperial March

Musical Tesla Coil + John Williams' Star Wars Music = Big Geek Fun

Oh yeah, and did I mention a dude dons some shiny Faraday fashion and takes the jolts.

Kids, don't try this at home.

(Tip of the tin foil hat to Frank Noschese and the AP Physics Listserv.)

New and used high-speed video

I'm in the process of organizing and adding to the content of my high-speed video page. The work continues, but much of it is done. And there are new clips aplenty.

Enjoy.