Tuesday, April 13, 2021

Teeeeter Totr

Just a quick balanced torque puzzle. It's really a test of whether or not one truly accepts the concept of center of mass.

Nothing exotic going on. The meterstick is uniform. Sufficient information is provided to solve the puzzle. It can be confounding to students.

Teeeeter Totr - HTML export | movie export

UPDATE: Among the many things I can count on life is that virtually any mechanics demo I might share here has already been done better by the inimitable Dan Burns. For example:

Sunday, April 11, 2021

RT;DL Pixel Peeping

Screens. When I was in school, screens were reflective white, flat curtains pulled down from retractible rolls when the teacher was going to show an educational film on the reel projector they shared with the other teachers at the school.

At home, screens were cathode ray tubes in which a spray of electrons, steered by magnetic fields and attenuated by a shadow mask, struck red, green, and blue phosphors. The high-pitched noise given off by the electronics of a CRT TV monitor create physical pain in modern-day students. TV watchers of a certain age somehow tuned that 10 kHz+ whine out.

Today, screens are everywhere, and virtually all are based on light-emitting diodes. But the RGB nature of color imaging remain. That's what this activity is about.

Color mixing and pixel geometry. Surprising enough and instructional enough to be worthwhile.

Pixel Peeping Student Document (Google Docs copy link)

Pixel Peeping Magnifier Observations - HTML export  |  Movie export
(media links are included in the student document)

The PhyzSommelier says this activity pairs nicely with

PhyzLab Springboard - Fun With Colors (Google Docs copy link)

Saturday, April 10, 2021

Thursday, April 08, 2021

In the George Floyd trial: Audio Pareidolia

Humans are so good at finding patterns, we often find patterns where none exist. This phenomenon is referred to as pareidolia. 

Add to this the power of suggestion, and things get even more interesting. The back masking panic was fueled by audio pareidolia. As was EVP: electronic voice phenomena, a means by which ghost hunters fool themselves and others.

I made a presentation on the audio version of this phenomenon and deployed it during our unit on waves and sound.

It was all good, wholesome, laughable fun. And then it showed up in the trial of Derek Chauvin. I have updated the presentation to reflect this latest incident. I placed it at the vary end so that by the time you get there, you'll recognize exactly what's going on.

Back Masking (HTML export)

Thursday, March 25, 2021

Polarized Black Hole Image

It's probably irresponsible for me to post this wee package that might deliver more questions than answers. Nevertheless.

Saturday, March 20, 2021

RT;DL Physics in the Fountain of Fizz

The Diet Coke Mentos geyser made a big splash in popular media before social media was a big thing. I was keen to incorporate it into my curriculum, but needed a content-based hook. Mythbusters (among others) focused on the chemistry of the spectacle. That was entirely cromulent: it's the engine that drives the demonstration. 

But I teach physics. And there's plenty of physics to exploit. Between the beginning and end of the eruption, some quantity of mass is ejected. Mass flow rate? Check. The fizz emerges from the bottle with some speed and reaches some altitude above the launch point. Energy conservation? Check. Determination of muzzle speed from maximum height? Check. Total energy dissipation approximation? Check. Power approximation? Check.

My school is a 1960s-era low-slung, sprawling campus. Determining the maximum height of the eruption is non-trivial. Most buildings top out at about three meters. We do have an accessible tall (~6 m) wall made of cinder blocks as part of our gymnasium. So that's what we settled on.

Initial mass is measured. Video is captured. Final mass is measured. The video is analyzed. Calculations are made.

Fountain of Fizz Student Document - Google Docs copy link

Fountain of Fizz Observations - HTML Export | Movie Export

Media links are included in the student document. The movie export is included for use on devices that struggle with the HTML export.

The Rainbow Connection—To Physics

Science Friday had a nice segment on rainbows.

The Rainbow Connection—To Physics

Seventeen minutes well-spent. Discussion includes tertiary and quaternary rainbows, why Hawaii is the rainbow capital of the world, and what rainbows might look on other planets (oh, that's a good one!).

Friday, March 19, 2021

Eight Days A Week

Here's a lesson plan organizer spreadsheet. It shows the classes I'm teaching and the cohorts assigned. All I need to do from here is flesh it out with some quality lessons.

Rinse and repeat. The sheet below accounts for the week of March 22. There will be 16 lessons each week for the remainder of the school year. Just gotta write 'em down and roll 'em out.

And then you woke up.

Actually, there are adult humans who imagine that this is something I will or should be doing. The coronavirus and "kids out of my house now!" fever have conspired to suffocate their logic and reasoning skills. 

Looking at that planner again, realize now that I left out the engaging but purely asynchronous lessons I need to prepare for Wednesdays. Good thing I can go back and edit those in.

Addendum 1: You might wonder why this is so much worse than pre-pandemic in-person instruction as it was in the Before Times. I have taught all of these courses before and know how to make each one work in-person. Those courses benefited from my 35 years for experience in the physics classroom.

Pandemic instruction throws me back to being a first-year neophyte in many ways. I have never worked so hard to be so ineffective. Not even in my first year of teaching in 1986-87.

Now it's hoped I can develop yet another thing that's never existed before: robust lessons for students who are physically distanced and thus cannot work in groups—but who are physically present in the science classroom. 

In addition to running the distance learning lessons that I have also never done before.

I'm sorry. I cannot do these things. Asking me to do them is abusive. I am already destroyed from the school year. I never had miracles to offer, and I certainly don't have any now.

Addendum 2: Instructional time for each course has been reduced from 288 minutes per week (59x2 + 123 + 47) pre-pandemic to fewer than 200 minutes per week (90 + 90 + 15) to 100 minutes per week (50 + 50). We lost one third of our instructional time for most of the year and will lose two thirds of our instructional time for the remainder of the year.

The district has worked hard to make sure students cannot access wifi on campus. Go ahead and re-read that if it didn't sink in on the first read. And after eight months of device-based instruction, the district expects that students electing to take their instruction on campus to go device-free for that instruction. District administration truly does expect "different but equal" in-person vs. remote courses to be prepared and implemented by instructors.


Addendum 3: Hybrid Cohort Logistics. In the future, people might not believe the contortions implemented by school districts. Best to document them while they're fresh in our minds.

A. The Weekly Schedule of Cohorts and Classes. Yes, I designed this myself. Color mixing and font choice were intentional.

B. The Daily Bell Schedules. The most important consideration here was that the start and end times matched the school's pre-pandemic start and end times. It's important to have priorities.

Wednesday, March 10, 2021

RT;DL Introductory Wave Activities

At this point, I think we all have our own favorite PhET sims. You might be able to start a fight among physics teachers by proclaiming your favorite is the best PhET sim of them all. But honestly, what's not to love about John Travoltage

Actually, I think Wave Interference is my favorite. (Energy Skate Park fans are now unfollowing me on Twitter.)

When we get to wave optics, we use the light module to develop interference pattern mathematics. As we begin the study of mechanical waves, we explore representations in the water wave and sound modules.

Water Waves in an Electric Sink (Google Docs copy link)
Students begin with examining a pulse with the sim's various view modes. Then it's on to continuous wave trains while varying frequency and amplitude.

High Quiet Low Loud (Google Docs copy link)
Originally developed for use with Pasco's Waveport DataStudio software, this activity has been redesigned around Wave Interference's sound module. This time, the manipulation of amplitude and frequency is accompanied with audio feedback. The sim's "Particle View" feature shows that matter doesn't move much even as a wave propagates across greater distances. Diving deeper, we notice that our sound waves appear to be moving through a solid in the sim.

I couple these with The Mechanical Universe - Episode 18: Waves and Paul Hewitt's Conceptual Physics Alive! Vibrations and Sound I and Vibrations and Sound II to round out much of the introduction to waves.

In any case, I'm sure there's even more to PhET's Wave Interference than I am leveraging. So much groovy wavy goodness!

Sunday, March 07, 2021

RT;DL Magnetic Electricity

The immediate follow-up to the Electric Magnetism activity is the Magnetic Electricity activity. As one might expect, Electric Magnetism explored the ability to produce magnetic fields using electric currents. Magnetic Electricity moves on to using magnetic fields to produce electric currents, with an emphasis on "moves".

Induced current and turning motors into generators are at play in this one.

Magnetic Electricity - Student Document (Google Docs copy link)

Magnetic Electricity Observations - HTML Export | Movie Link

Media links are included in the student document. The HTML export is preferred. The movie export is available for use on devices that struggle with the HTML export.

Saturday, March 06, 2021

RT;DL Electric Magnetism

With Ørsted's Discovery, we established that electric currents are surrounded by magnetic fields. In this activity, we extend that to the design of electromagnets and motors. In our traditional, In-Person Learning electricity and magnetism sequence, we would have used our Genecon hand-crank generators to power electric circuits. In short, we would have been familiar with their utility as generators. Here we turn the tables so that the Genecons become motors.

This one is also a bit fiddly in class: St. Louis motors are great, but students will discover all the ways they can go wrong. I don't think that's a bad thing, but there is frustration in the room. You lose that in the RT;DL version. You lose a lot in most RT;DL activities.

But it's a nice sequence of observations, building on Ørsted's Discovery and setting up the next activity: Magnetic Electricity.

Electric Magnetism - Student Document (Google Docs copy link)

Electric Magnetism Observations - HTML Export | Movie Export

Media links are included in the student document. The HTML export is preferred. The movie export is available for use on devices that struggle with the HTML export.

Enjoy my lack of professional production sets, lighting, and technique. These are all shot in my classroom using classroom apparatus and lighting options, and shot on my iPhone 8. Presentations are created in Apple Keynote and exported as HTML and exported as a movie.

One More Thing: I just noticed this delightful bit of apparatus available from Arbor Scientific. Simple and effective for working out the right-hand rule for the magnetic force on a current-carrying wire.

Monday, March 01, 2021

RT;DL Ørsted's Discovery

This activity explores the magnetic field around a current-carrying wire: Ørsted's Discovery. It's a bit fiddly when we do it in the classroom. The compasses can be thrown off by steel spines and/or leg plates in the tables. To be honest, I've seen compass behavior I cannot explain in my classroom. Perhaps strange things happen to our compasses while they're stored during the off-season. They are stored in proximity to bar magnets.

In any case, I got passably reasonable behavior from my compasses as I recorded the videos for the RT;DL observations of this activity.

Because I was recording the observations on behalf of the students, I provided them to the students in a disorganized way. Students would need to match the randomly sequenced observations with the called-for observations in the activity instructions. It's RT;DL ... you do what you can.

The HTML reports are preferred; the movie exports are provided for users whose devices struggle with the HTML exports. Links to all media are embedded in the student document. 

Apologies for any clumsiness that comes through in the videos. The physical geometry required for recording these events is awkward, and I really didn't invest much time in rehearsal. I was happy to get decent light on my subjects.

Ørsted's Discovery Part B (3D) - Movie Export

Ørsted's Discovery - Student Document (Google Docs copy link)

Ørsted's Discovery Part A (2D) Observations - HTML Export | Movie Export

Ørsted's Discovery Part B (3D) Observations - HTML Export | Movie Export

Friday, February 26, 2021

RT;DL Seeing Magnetic Fields

This activity shows a magnetic field projectual being used to reveal the magnetic field around various configurations of bar magnets. As with all RT;DLs, this activity began as an in-class lab and has been retooled for online delivery. 

Seeing Magnetic Field - Movie Export

Seeing Magnetic Fields - Student Document (to make your own copy)

Seeing Magnetic Fields Observations and Mysteries - HTML Export (this link is in the gdoc, too)

Seeing Magnetic Fields Observations and Mysteries - Movie Export (for devices that cannot run the HTML export—this link is in the gdoc, too)

I will confess that I find watching iron filings slowly align with magnetic fields on a large screen to be calmingly satisfying. I suppose it's my ASMR.

Thursday, February 18, 2021

Early Retirement

When I hatched it, I referred to my plan as “23AndMe,” like the genetics company. I would “graduate” (retire) in 2023, after teaching physics (and other things) at Rio Americano High School for 37 years. I was excited when my graduating class arrived on campus last year.

The CalSTRS numbers looked good. The last few years were going to be a bit bumpy, though. Physics, a course I've taught at Rio since 1986, was coming to an end. The vision of Next Generation Science Standards called for Physics to be replaced with Physics of the Universe (PotU). 

California published its vision of PotU, but textbooks and curriculum have been slow to emerge. The widespread expectation is that classroom teachers would absorb the NGSS PotU vision and leverage their creativity and ingenuity to develop curriculum ex nihilo. I had done some preliminary organizational work on how I would implement PotU at my school. But that first year promised to be an endeavor. There were two teachers at my school who could teach physics after I was gone. We met a few times to work on PotU.

In January of 2020 (years ago, now), my district offered a wee early retirement incentive to its oldest and most educated teachers. They hoped to clear out the highest paid faculty, easing pressure on a strained district budget. I looked at the numbers and was insulted. No way.

Then the pandemic struck. The district rescinded the incentive to those who applied for it. Many teachers retired without the incentive.

Our Last Day of School was Friday the 13th of March, 2020. Novel but unspectacular when it occurred. 

We have yet to return. Teaching is remote; learning is distant. It is awful. The school’s younger physics-teaching prospect moved to another district. An intended textbook adoption for all science courses was suspended.

For 2020-21, I had four preps: Physics, AP Physics 1, AP Physics 2, and Conceptual Physics. Transforming each of these classes to online versions has been ... difficult. And, to be delicate, the efficacy/effort ratio has not been high. I'm maintaining a headache that doesn't show signs of subsiding. My screen time exceeds any health-conscious dosage recommendations. 

In November, my district offered the same wee early retirement incentive. Same exact numbers as it offered in January. But they looked quite different to my newly throbbing eyes. Less insulting and more inviting. Bordering on irresistible

There's a significant pension prize if I stay the course for two more years. But here’s what I'm looking at. 

The course I polished over 35 years will be gone. A course I’ve never taught will take its place. There may or may not be a new textbook for the new course. There will be no 180-day curriculum with pacing guide/road map for this new course. No lab manual. No new lab materials. No test bank. Teachers might be given "release time" to develop such during the summer and/or during the year. Scratch that: there will be no budget for such extravagances. 

In fairness, this was what I walked into in 1986. I developed my course on my own, with direct and indirect help from mentors. And I was happy to do the work. Hard work. But I was bringing my vision of the course to life within my operational constraints. And I got better and better at loosening those constraints. The enterprise was enjoyable, challenging, and engaging. I was supported by the school and parents. I knew I was playing a long game, so I mixed patience with my determination.

What's happening now is different. I'm being compelled to implement a vision I was not invited to create. This has been true of the redesigned AP Physics 1 and 2 for a few years, and has not been enjoyable. Doing the same with the new Physics of the Universe does not appeal to me.

Predictions are difficult, especially when the future is involved. But it’s hard to see school districts in the next few years being flush with enough cash to fund curriculum development. Or anything else. We’ve had furloughs in the past. I don't see good times ahead for school district budgets. My district is keen to replace me with someone lower on the pay scale. The budget is prioritized over instructional quality. But that's always been true; you a priori-tize that assumption going in, and do well because it's important to you.

The recently-redesigned AP Physics 1 will certainly still be there. I haven't made a secret of my antipathy for that redesign and especially for the accompanying exam. But the College Board has convinced themselves that they are doing good in the world and so they will continue. Schools use AP courses to market themselves, so AP will continue as a thriving product line. I enjoy the course; I don't enjoy the test-prep aspect.

AP Physics 2 is a bit more on the bubble. It’s a tough sell, a second year of AP Physics in high school. My principal has made it a priority to run it, and I love teaching the material. To me, much of the AP2 material is more interesting than what we do in AP1. The district is in the process of adopting a new textbook for AP Physics 1 and 2. Our current textbook is ©2007 and was pretty shiny when we adopted it for AP Physics B in 2008. That was the last time we adopted physics books, now 13 years ago.

So two years of a developing course and one or two AP courses whose exams have lost their lustre. In a world of no books or piloting new books. With budget cuts looming. While we await full implementation of vaccines in a nation where anti-vaxxers stand loud and proud. 

Which part of that seems unappealing, right?

When I envisioned 23AndMe, Physics was transitioning to Physics of the Universe in a controlled manner with the participation of colleagues who would be left in charge of teaching it when I was gone. I actually designed the transition process for my school. The economy was such that I could expect a raise to be negotiated before I retired. And I had not experienced Remote Teaching/Distance Learning of four courses for the better part of a school year. 

There's more about short- and long-term issues that have altered my perspective, but this post has self-indulged quite enough (even for a blog post). Anything else I need to say will be posted in the comments. I'm dropping this post like a bread crum in case I ever wonder "What was I thinking?" in the years to come. (As Sade once sang, "The rose we remember, the thorns we forget.")

I think it's time for me to turn the page and move on. As the implications of this life-change settle into my features, I feel some subtle tingles of a weight being lifted normal force being reduced. 

I'm 35 years into the career. No one who was working at my school when I arrived is still there now. "Early retirement" feels like a misnomer. CalSTRS estimates over 16,000 California teachers will be retiring this year.

Wednesday, February 17, 2021

Practical masking advice from Professor Marr

Rio Americano alum and Virginia Tech professor, Dr. Linsey Marr, was a guest on NPR's Science Friday. Host Ira Flatow asked her a tight sequence of practical questions, and she handled them all with aplomb. 

In my years of science lectures, colloquia, and conferences, I don't need that many fingers to count academics who communicate as effectively as Linsey Marr. And just because I'm biased, it doesn't mean it isn't true. Am I proud to the point of bursting? Pretty close. 

Judge for yourself:

Two Masks Are Better Than One - Science Friday 2/12/21 - Professor Linsey Marr (16:58)

Oh, and you'll get practical information on how best to handle the pandemic as it stands in February, 2021.

Monday, February 15, 2021

Just in time for Valentine's 2022!

Somewhere along the line I added four Scientist Valentines to my personal collection and failed to add them to the Flickr album. Why? I don't know. But I'm here to make it right. With ample lead time for Valentine's Day 2022. In any case, the collection expands from 24 to 28.

Scientist Valentines aficionados will have no trouble spotting the new items (two female; two male). I have a favorite, but I'm not saying.

Scientist Valentines

Scientist Valentines

Thursday, February 11, 2021

RT;DL Van de Graaff Demonstrations

What may turn out to be the most shocking (yeah, that didn't take long) aspect of my Van de Graaff demonstration sequence is how I could possibly have left your favorite VDG demo out. What was I thinking? By all means, let me have it in the comments—don't hold back.

Charging Ahead - Movie Export

If you can forgive me, I selfishly included all of my favorites. And they're not so bad. My favorites are ones I can mine for good physics that I believe my students can gather and grasp. 

Mop Head, Pie Tins vs. Styrofoam Bowls, Bubble Brigade (soap bubbles), Bad Hair Day, Green Wig, and I Blew My Top. Again, light me up in the comments for omitting the cool VDG demo you do.

There is also an explanation of how the generator works.

Sunday, February 07, 2021

RT;DL Electroscopia

Here is the second qualitative electrostatics lab redesigned and video clip enhanced for use in Distance Learning. The first was "A Pithy Matter" shown in a post below.

For "Electroscopia," we swap out the pith balls for a can form electroscope. These were sold with cardboard inserts with angle markings to make them more electrometer-ish. In practice, removing the insert allowed students working on opposite sides of the electroscope to see the pointer without obstruction. 

The activity works through a series of observations involving charge typing, induction, and the differences between conductors and insulators. It closes with some questions students should be able to answer with the benefit of evidence. 

There are appearances of the Fun Fly Stick, a latex balloon, and my head in this activity. Not to be missed!

Here's a taste.

Electroscopia - Student Document (Google Docs copy link)

Electroscopia - Observations (HTML export, preferred—linked to in the student document)

Electroscopia - Observations (Movie export for devices that struggle with the HTML export)

Mystery Objects and Mystery Charges - (HTML export for use by instructor while students collaborate in breakout rooms)

In practice, students "ask for help" to summon the instructor to their breakout room. Once there, students request an Object or a Charge and identify their room number. The instructor shares their screen while showing the appropriate clip, then leaves the breakout room as students interpret the observations.

Saturday, February 06, 2021

RT;DL A Pithy Matter

Sure, there's some kind of force involved in the rubbed plastic/pith ball interactions. But do we really need to consider it a whole new force? Isn't it just some form of gravity or magnetism? Let's experiment.

This qualitative exploration of electrostatics features: electrostatic attraction and repulsion, a triboelectric sequence (but we don't use the T-word here), an electrophorus (with pronunciation guidance), and two rounds of Pith Ball Ping Pong. What's not to like?

Let me just add that nothing—nothing—turned my most jaded, been-there-done-that high school seniors into elementary students more than this activity. When the pith balls started flying, their giddy glee was an involuntary reaction that expressed itself before they could so much as attempt to stifle it.

A Pithy Matter - Student Document (Google Docs copy link)

A Pithy Matter - Observations (HTML export as linked within the GoogleDocs document). This is a sequence of video clips showing interactions between cloth-rubbed plastic and pith balls, with special appearances by an electrophorus (ft. slow-motion electrophorus ping). Here's the movie export of the observations for use on devices that struggle with the HTML export—link also included in gdoc).

A Pithy Mattrer - Special Observations (HTML export for use by the instructor). They will seem silly to experts with content knowledge, but they are actually critical for the purpose of this activity.

This activity was designed for use with video conferencing (e.g., Zoom). Students need to check in with the instructor to see the "Special Observations". It's a redesign of what was an in-class lab. I consider it a mark of success that I am able to use the same lab quiz (ported to Socrative for online use, of course) to assess student performance on the activity. 

The roughest edge for students in this activity is recognizing that the brick is far and away the "most gravitational" object in the apparatus and how it can be used in this lab. The instructions make an attempt to steer, but still... Once they get past that, most groups catch on to the value of the bar magnet. Most; not all. 

To the best of my knowledge, this activity is not duplicated or even simulated elsewhere in teh interwebz. No Pivots; no PhETs. I will be corrected in the comments if I am mistaken.

In Distance Learning, I'm everyone's lab partner in addition to being the instructor.