Buy that special someone an AP Physics prep book, now with 180 five-minute quizzes aligned with the exam: 5 Steps to a 5 AP Physics 1

Visit Burrito Girl's handmade ceramics shop, The Muddy Rabbit: Yarn bowls, tea sets, dinner ware...

02 June 2020

Where I stand, and why I focus on physics

I'm finding it hard sometimes to think about physics while the country burns... when my saying "I am anti-fascist" has somehow become a controversial and provocative statement rather than the social norm I assumed all my life... when I have students and colleagues who need support.  I suspect I'm not the only one having trouble.  

Yet... physics has been the primary way I've connected with the very people who need support right now.  Teaching physics, reading physics exams, working with physics teachers, is what I do, is what I've done since 1996.  It's the way I have made connections with all sorts of people.  It's a way I contribute to the worldwide community of physics teachers and students.  

I'm going to be professional and focused on the AP Physics reading for the next two weeks.  And then on my summer institutes - conceptual and AP - for the six weeks beyond that.  I'll probably post a bit about physics and physics teaching throughout the summer, as I always do.

I just don't want you to think that my laser focus means that I don't know or care about the world beyond AP Physics.  I know and care.  I stand against fascism, against state-sanctioned violence directed toward peaceful people.  And I know that you do, too.  Stay safe.

24 May 2020

Physics professional development summer 2020: Conceptual Physics Summer Institute (Space available in July - August session is filled!)

Update June 26: The August 1-2 session is filled.  Still about 12 spots available for July 25-26!

Folks, I'm already teaching a bunch of AP summer institutes - you can find details here.  But what if you are looking for physics professional development that is NOT aimed at college-level physics?  I mean, I meet so many of you each year who teach on-level, honors, college-prep, Regents... to all ages, to all varieties of student.  And in my personal mission to spread physics knowledge to as wide an audience as possible, these sub-college courses represent a critical first point of contact with our discipline.  I focus as much energy on my conceptual course as on my AP course each year.  So I'd like to focus some of my summer professional development expertise on those who teach these first-level courses.

I'm offering a two-day institute on August 1-2 2020 (filled) or July 25-26 2020 (space available).  (Online, obviously, broadcasting via Zoom from my lab.)  Skip past the institute description for fees and registration instructions.  The course will be limited to the first 30 who sign up.  The daily agenda is included here at the bottom of the page.

Jacobs Physics
Conceptual Physics Institute Description
August 1-2 2020 or July 25-26 2020

All levels of high school physics can be taught conceptually – where verbal and experimental reasoning is prioritized over mathematical problem solving.  While mathematics are used extensively, they are used as a tool to create predictions about the workings of the natural world.  Whether you teach “general”, “on-level”, “honors”, “Regents”, or “college-prep” physics, a conceptual approach can be adapted to most any introductory physics topic – and to most any state or district standards. 

In our institute, we will discuss, practice, and share methods of teaching common physics content in a conceptual style.  I will be broadcasting from my laboratory via zoom.  Time will be devoted to experimental methods that are especially useful at the sub-college level; to course planning on a year-long and a unit basis; and to best-practices physics pedagogy, which differs substantially from pedagogy in other disciplines.

Participants will be given a full-year’s set of classroom-ready materials, including fact sheets, in-class and laboratory activities, assessments, and planning documents.  More importantly, through their interactions with the instructor and with their colleagues, participants will develop skills and ideas for adapting these materials to their specific classroom environment.  Those attending will also earn a certificate indicating their participation in 15 hours of physics professional development.

How much does it cost:  $200 for the weekend.  The schedule of events is listed below.

How do I register?
(1) Click the "donate" button below (or in the left column of the blog).  It will take you to paypal.
(2) Enter $200.00 as the donation amount, either through paypal or credit card
(3) Click "Add special instructions to seller" or "Add a note"
(4) In the note, please include your name, preferred contact email, and institution
(5) Fill in payment info and click "donate now"

That's all - I'll be back to you within a day or two confirming your registration, and sending you links to the classroom-ready materials.

Cancelation issues: If you register then can't attend, contact me via email.  As long as I can replace your spot, I'll send a full refund; if I can't replace your spot, I'll refund all but $25.

Schedule: Each session will include both whole-group presentation/discussion, and breakout groups for activities.  In between sessions and during breaks, Greg will be available for informal conversation. 

Saturday 1 August or 25 July (all times eastern time)
9:00                 Introductions
                        What does “conceptual” mean – defining levels of physics
Different levels of physics: developing your program
                        Different levels of physics: developing your resources

10:30               Eight styles of physics laboratory activities
            Including the two best-adapted for conceptual physics
My first day activity – reflection experiment
My first group laboratory experiment – refraction

12:00-12:30    break

12:30               Sequencing your course
Starting the year right: the most important physics teaching skill
Justifying answers with facts
Simple ray diagrams for optics in conceptual physics
Justifying answers with equations
In-class laboratory exercises: circuits

2:00                 The daily “quiz”
Tests and quizzes, targeted to different levels
                        Other sorts of assessment
                        Preparing for the trimester/semester exam
                        Adapting a conceptual course to external standards
                        In-class laboratory exercises: motion graphs

Afternoon – asynchronous
                        Read through the shared files
                        Read through the Jacobs Physics blog
                        Adapt to your district or state standards
                        Bring questions and ideas for the social or for Sunday

7:30                 Optional Zoom social: Dinner, dessert, drinks, and conversation.  BYOB, obviously. 

Sunday 2 August  or 26 July 
9:00                 Building and creating experiments with whatever you’ve got
                        Developing your own in-class lab exercises
                        Using or substituting inexpensive equipment
                        In-class laboratory exercises: direction of force and motion

10:30               Methods to speed your grading
                        In-class laboratory exercises: forces in 2-d
                        In-class laboratory exercises: motion in 2-d
12:00-12:30    break

12:30               The final third of the year – once skills are built
                        How I teach impulse/momentum
                        Energy bar charts at the conceptual level      
                        Laboratory exercises with harmonic motion

2:00                 Sharing: Any Other Demos
Online simulations:
                                    The Physics Classroom
The Physics Aviary
                                    Vernier’s Pivot Interactives
                        Ending the year: the Physics Fight



05 May 2020

Leave checkboxes for last - start with evidence and reasoning.

In my time teaching, I've coached baseball, football, tennis... and debate.

A common way of teaching students to structure an argument is via “claim, evidence, reasoning.” The debate team uses this in their cases – it’s an excellent way to communicate. The AP exam often encourages this structure by first asking you to check a box to indicate your answer; then, to justify your answer.

To many of you, this brings back bad memories of your 7th grade math class. You knew the answer instantly, because good smart boys and girls always know the answer. And you knew that the teacher knew the answer. But your teacher marked you wrong – “you need to show your work.”  What? Why? This is stupid, I really need to show you how I solved “7-x=3” for x?  The answer’s 4. Justify my answer? Because math and logic. Duh.

And this teachery obsession with “showing your work” extended throughout much of high school.  Okay, the problems got harder, but you still could do them without laying out reasoning step by step as if you were a stupid person. Teachers are so condescending.


In physics, good smart boys and girls aren’t expected to know the answer. In fact, the teacher doesn’t know the answer to a new physics problem.

Really – I’ve been doing physics since 1990. When I see a free response question, I don't know the answers. I figure them out – I start with facts of physics, continue with an energy bar chart or free body diagram, and come to a conclusion.  

I don't do “claim-evidence-reasoning.”  I do “evidence-reasoning-claim.”

When my students do test corrections, they invariably get hung up on the right answer. They might convince themselves that the answer is that the amplitude increases after the collision.  Then they twist and turn facts and equations to show increasing amplitude… and get more and more frustrated with me as I show them their incorrect logic.  Eventually they get every logical step correct, and say “therefore the amplitude increases."

It never occurs to them that their conclusion might be wrong!

My students are like the evil prosecutors on shows like Law & Order or Matlock… we know this person is guilty, how can we arrange the evidence to convince the jury of their guilt?

That’s not how it should work!  You start with the evidence – based on this information, who is most likely to have committed the crime?  Perhaps if more lawyers and police officers were physics majors, our criminal justice system might be improved.

So don’t be the evil prosecutor. Don’t identify the murderer and then cook the evidence to frame them. Instead, on the AP exam, leave the checkboxes blank until you’ve written your justification.  Then, only then, come to a conclusion – and check the box to say whodunnit.

04 May 2020

When is something a "point object"?

I've gotten the question a bobzillion times since I did a show about angular momentum

I know you said angular momentum is L=Iw* for an extended object, and L=mvr for a point object.  But how do I tell whether something is an extended object or a point object?

* Yes, folks, I committed sacrilege - I wrote the variable for angular velocity not as a Greek omega, but as a Latin w.  And I've neither been struck by lightning, nor lost points on my AP exam.  

Consider the size of the object itself, and then consider the distance from the object's center to the axis of rotation.  If the distance to the axis of rotation is considerably bigger than the object's size, then you've got a point object.

A meterstick pivoted at one end? The distance from its center to the axis of rotation is 50 cm; the object length is 100 cm.  Not a point object.

The ball I shot at a wooden stick during the linked show? The ball was maybe 2 cm across.  The ball hit the stick about 9 cm below the stick's center, which was indicated as the axis of rotation for angular momentum conservation.  So we can consider the ball a point object in this case!

(That same ball rolling down a ramp, with the axis of rotation being the ball's center? That's gotta be treated as an extended object, because there is no distance at all between the ball's center and the rotational axis!)

What does r mean, then, in L=mvr? Isn't that the radius?

No, in the equation L=mvr for the angular momentum of a point object, r represents the "distance of closest approach" - extend the line of the object's motion, and find the closest that line gets to the axis of rotation.  That's r.

And how can something moving in a straight line have angular momentum, anyway?

If you're an AP physics 1 student: it just does.  L=mvr for a point object moving in a straight line.  That's, for now, simply a fact of physics.  If you're in AP physics C or above, you can ask for further detail in the comments, but only if you already understand the mathematics behind vector cross products.

No seriously!  One of the major obstacles to first-year students understanding physics is that they see the deep vector calculus reasoning behind some ideas, usually in a textbook or in wikipedia or from their teacher in response to the fastest student in the class... and they think they're supposed to understand every bit of the reasoning, they don't, and they lose confidence.  It's like trying to teach three different kinds of curve balls to a 10 year old pitcher, or the 1996 Chicago Bulls Triangle Offense to a middle school team.  Don't!  

For now, just use the L=mvr formula as a fact of physics.  You don't need to go any deeper than that for AP Physics 1!

01 May 2020

2020 AP Physics exams: Type your answers. Really - TYPE YOUR ANSWERS.

I keep getting questions from people, even people who have read yesterday's post from associate chief reader Matt Sckalor.  They know that Matt and I and everyone associated with the 2020 AP Physics exams says to type your answers.  And yet, they keep asking "wait, but what if the exam asks for derivations" or "but what if we have to draw a diagram" or "but what if the readers take off for..."

I mean, Matt and I and everyone have made it clear as many times as we know how - no drawing diagrams, no derivations, prose is sufficient for everything.  What more can I say?  Do you think I'm going to come out with an evil laugh, ha ha ha ha! Fooled you all! You FAIL now!"?!?!

Look.  I'm a table leader at the reading. I don't want to read fancy formatted equations - I want to read typed prose.  I'll read whatever your student submits, 'cause I'm a professional... but I want to read typed prose.

Let's say a student types "with initial speed zero, the relevant equation is d=1/2at2."

I know what that means - it's very clear.  So does every reader.

But Professor Milhouse says, "Well, actually, that equation doesn't expressly indicate the groupings under the fraction.  The student might really mean one over 2at2.  That's equivalent mathematically to the reciprocal of four times a times t.  That's not a physics equation!  I am certainly not accepting that for credit!"

Um, Professor Milhouse won't last long at my table.  Nor at anyone else's.

Please emphasize to your students that we are physicists, not lawyers; please emphasize to communicate physics as best they can, and not to fear "omg, what if I lose a point because..."

Your students will get credit for good physics.  They will not get credit for bad physics.  That's it.  No matter how they submit.  But it'll sure, sure be easier on them and on us and on EVERYONE if they'll just type.

29 April 2020

The Word about the 2020 AP Physics 1 exam - from Matt Sckalor

Folks, you're hearing a lot of stuff about the format of the AP Physics 1 exam this year.  Most is baloney, as I've referenced before.  We do know that there will be two free response problems: one qualitative-quantitative translation, and one paragraph response.

If you don't know Matt Sckalor, he is the associate chief reader for AP Physics; he's one of the best physics teachers in the world; and, he's on the P1 development committee.  His word is the Word of God when it comes to AP Physics 1.

He posted to the AP teacher community with advice for our students about how to submit answers to this year's unusual exam administration.  With his permission, I've included that advice below. 

Your students can practice what Matt suggests by going to  This is the authentic website where the College Board wants you to practice submitting copied-and-pasted work.  They should try it out!

From Matt:

Having had experience grading handwritten and scanned AP exams, I highly recommend you encourage your students to type their responses.  The exams are specifically written to be answered in prose; words.  No diagrams, no graphs, no algebraic manipulations.  This has been repeated numerous times.  Chemistry and Calculus have different things going on that require a keyboard guide to help students answer on a keyboard.  That’s not us.  Many practice questions that are out there have aspects that may require algebraic manipulations or complex equations or derivations.  Those aren’t the test questions.

Can they USE equations in their response if they need it to explain their answer?  Of course. 

They can type equations like this: x = Vo*t + 1/2 a*t^2.  Or Fnet = mg sin theta.  Or L = I x omega.  Readable, yes?  No fancy equation editor needed.  In fact, if you try to insert an equation in Word, it’s inserted as a picture, which will NOT paste into the text field of the exam, and the guide says NOT to include pictures in your uploaded documents.   The guide is very clear, tell your students the three ways to submit their answers and be clear on the file types and specific instructions.

If, despite the benefits of typing, your students wish to hand write (and there are valid reasons for some students who wish to do so), implore with them to make sure to write darkly, legibly and that their work is organized.  Then above that, the picture should be in focus, well lit, include the entire document in the frame and they need to check it to be sure its readable!  As I said, I have seen photos of student work that even zoomed in and color corrected could not be read.  Some didn’t press hard enough on the page, some had the edge of their paper cut off, some just had work scribbled all over the place.  You will get their work back at the end of May and you can judge for yourself.  If you are an exam reader, you already know this.

And whatever device they click their e-ticket on is the device they should upload from.  That doesn’t mean they can’t type their work on another device, but they will need to transfer that work onto the device the exam is on.  In Google docs, that’s automatic.  Otherwise, they can email it, airdrop it, use dropbox, etc. 

Frankly, they will have enough to deal with taking the exam and answering the question, I don’t know why people are presenting more complicated scenarios, we should advise them to keep it as simple to complete as possible; one device, open and read, type, copy, paste, submit.  They are permitted to print the exam question on paper as well if they want to avoid scrolling and multiple screens.  You know your students and if they’re like some of mine, and if the instructions are more than 3 lines, there will be students who can’t follow it, and the cost is a zero on the question.

21 April 2020

Come to my AP Summer Institute... from ANYWHERE!

Folks, I know we're all in AP prep mode and novel-online-learning mode and survive isolation mode... but I'd like you to give a thought to your summer plans.  Depending on your location, there might never be a better time to attend one of my APSIs.

This year - and this year only! - I'm going online.  That means that even though, for example, my first institute is through Walton HS in Marietta, Georgia, I will be teaching from my classroom in Virginia - and you can attend from anywhere.  Now's the time to ask your school for funding.  No travel costs, no hotel costs, just pay for the institute.  

How does an online APSI compare to one in person?  (1) It will not, simply can not, be as awesome as when we're all in the same room doing lab work together, eating lunch (and sometimes dinner) together, even heading off to baseball games together. (2) It will nevertheless be fantastic.

In four days, we will discuss all sorts of how-to-teach physics ideas.  This will be your chance to ask me follow-up questions to blog posts, podcasts, youtube shows.  I'll let you know official College Board gospel about how AP classes work and how the exam works.  I'll give you some behind the scenes information from this year's (and many other years') reading.  I'll teach you how to grade an exam problem.  

Most importantly, I'll teach some of my classes so you can get a sense of the pedagogy I use and the content I teach.  I'll share with you gigabytes worth of files that are classroom ready for you.

Whether you're brand-new to teaching physics, or whether you're a veteran who'd like to learn new things and share your own ideas with others, you will find this institute useful.  In fact, this year in particular, I encourage you to sign up with a department chair or with another physics teacher at your school - it'll never be more affordable financially, it'll never be easier logistically.  (I mean, if you have your own kids at home, taking a week away is difficult - but taking a week-long online course from home is way less difficult!)

Each institute runs four days, Monday-Thursday.  We'll have live sessions in the morning and early afternoon; then in the mid-afternoon I'll make myself available for further questions while you have a chance to dig in to and ask about supplementary material such as the course description, AP classroom, my gigabytes of files, released exams, etc.

The first is through Walton High School - click the link for information and a registration link.  That's June 22-25.

The second is through the non-profit PWISTA and Purchase College.  That's June 29-July 2.

Here's the College Board link to the TCU institute, July 6-9

[Update June 8: I will no longer be doing the University of South Florida institute.]

Please contact me through twitter (@gregcjacobs) or through my Woodberry Forest School email if you have questions.  I'd love to see you - virtually - this summer!


20 April 2020

Understanding experimental physics is critical - even in 2020 with no lab design question!

I'm often asked, "Give me a straight answer - will experiments be tested on the 2020 online AP Physics 1 exams?" 

The straight answer has two parts: (1) While in a normal year one question is devoted predominantly to experimental design, such a question will not be included on the special 2020 exam.  (2) All physics refers to real experiments. You must therefore understand the physical -not just mathematical - context of every question!

Here's how I explained this on the April 8 AP prep show:

I teach at Woodberry Forest School, a country club for dogs in central Virginia.  Or, at least that’s what our empty campus feels like in the evenings, as the faculty take their nightly dog walks en masse – a mass of dogs. Usually, the dogs are far outnumbered by 400 boys living in the dorms.  And I long for those usual days to return.

We know what kinds of problems you’ll see on the AP Physics 1 exam on May 14.  The second problem will have a 15 minute time limit, and will ask you in large part to respond with a “clear, coherent, paragraph length response.” Think of that the same way you’d think of a “justify your answer” question – just use about five sentences instead of about two.

The first problem will have a 25 minute time limit, and will be a “qualitative-quantitative translation” question. Think of that as just a normal physics problem, but one unlikely to use numbers. You’ll be asked to relate algebraic expressions to physical behavior. That is, here’s some math, here’s an experiment, explain what features of the math explain the behavior of the experiment.

Notice I said “experiment.”  Wait, I thought the “experimental design” question wasn’t on the 2020 exam!  It’s not.  But every physics problem that can possibly be posed must be based on a real experiment – otherwise it’d be an abstract mathematics problem, not a physics problem.

See, that’s what physics is, at its very heart – predicting how the natural world behaves, using mathematics. 

So don’t be surprised when that first question asks something like “What would happen if we increase the cart’s mass?  Explain without using equations.”  You will have to use your experience, along with a conceptual understanding of physics principles, to imagine and describe how an experiment would behave. 

How do you prepare for this kind of question?  By doing the kinds of problems that you've been doing all year - including experimental design questions. Not just “what is the numerical value of the cart’s acceleration” but also “how would that acceleration change and why,” “explain in words how you determined the cart’s acceleration”, and even “what does an acceleration of 4 m/s2 mean about the motion of the cart?”  In other words, just do physics.  And that includes an understanding of how mathematics describes... experiments.  

15 April 2020

How do I prepare for the AP Physics 1 exam? You *taper*.

[This was what I said during the introduction to the AP Physics 1 youtube show on April 6.]

Hi hello and welcome… I’m Greg Jacobs.  I teach at Woodberry Forest School, a boys boarding school in central Virginia.  

In the Before Times, I’d be sitting here at my desk with music playing while 15 or so students worked in the lab behind the camera… talking to each other about practice problems, showing me their work, doing experiments.  April is the best time of year in AP Physics 1 – the time to put it all together, to figure out not just how to use the disparate skills you’ve been taught, but when those skills should be applied in the first place.

And the time to do the putting it all together is now.  Learning physics is like preparing for the conference swim championships.  See, my wife Shari was a college swimmer.  She spent December and January in gruelling multi hour practices building muscle and technique.  (She was so tired from these that she often didn’t have the energy to walk across campus to get dinner – she’d instead eat five or so of the excess grapefruits that I was sending her from my backyard tree.)  But then in the weeks before the championship, the team tapered.  They still practiced every day, but less and less intensely.  The goal was to maintain, not to build.

And so it is in physics. You’ve spent the year building your knowledge. Now it’s time to start tapering.  Do a released AP problem.  Don’t ask for help, don’t ask “clarification” questions, just do the problem as if it were an exam. THEN, show your work to a teacher or a friend, or even to me. Right or wrong, you’ll have learned something!  It’s totally fine to make a mistake – in fact, now’s the time to make mistakes, so you don’t make them on the exam.  Redo the problem, though, until it’s right.  Then move on to another one.

The goal is to do a little bit every day to maintain your physics skills.  See, if you’re watching this, you probably are taking more than just one AP exam.  You’ll be so busy in May that you won’t have time for serious, in-depth physics study.  So don’t plan on that!  Plan on doing one multiple choice practice question a night in May… and the night before the exam, plan on having a not-physics party.  

When I taught in Florida, my night-before-the exam party was on the beach.  Here, it’s been at the pool or in the snack bar. There’s nothing you can do the night before the exam, any more than a football team can build strength through a 4-hour weightlifting session the night before the Rose Bowl.  So work now… make your mistakes now, correct your mistakes now, and you’ll build your confidence for May 14.

02 April 2020

Why are we here? Why teach physics during a global plague? Because science MATTERS.

(The following is a transcript of the introduction to today's live AP Physics 1 show...)

Hi hello and welcome… I’m Greg Jacobs.  I teach at Woodberry Forest School, a boys boarding school in central Virginia.  Our campus is beautiful this time of year! Historically I would be spending afternoons umpiring high school baseball games, or broadcasting Woodberry games over internet audio – and I’m sad, so sad, to lose those and other spring rituals.  But as two of the Four Horsemen ride, I recognize that baseball simply doesn’t matter right now.

So why are we here, then? I mean, I am grateful to you for listening, for engaging over twitter, for being the community that you and I both need.  Let me give a shoutout to Cypress Ranch High School (Go Mustangs!), who are arranging a virtual watch party with their physics teacher for each epidosde!  But the question remains… why bother with physics in these apocalyptic times?

I know many of you are here because your teacher or your parents are making you watch.  And some of you make yourselves watch – you want to do well on the AP exam, to earn college credit, to demonstrate your knowledge of physics to you and your teacher.  I’ve no doubt that some audience members have come to love physics for its own sake – the universe is amazing, and in AP Physics 1 you’re taking the first steps toward understanding how the universe works.  And some of you are here for the Edna fan art – thanks, @Aldescery, your drawings have made me smile more than anything else these past weeks.

I’ll tell you an important reason why *I’m* here.  Not just here today, but here in this profession.  See, science matters.  Physics – and chemistry and biology – teach an understanding of the universe based on observable, measureable evidence.  AP Physics 1 is a useful gateway to science because the experimental evidence in this course is human scale, can be acquired (except, perhaps, for gravitation) in your classroom.  The answers to physics problems aren’t right because your textbook said, or because the President   of the American Physical Society gave a press conference.  Answers are only correct if they are supported by experimental evidence.  Josh and I have been showing you not just answers, but evidence for those answers.  That’s science.

Once you understand introductory physics and its human-scale experiments, it’s easier to understand chemistry and biology – the evidence underlying biology generally requires microscopes, PCR machines, DNA elecroferesis, all these more abstract techniques than just a photogate or a spring scale.  Nevertheless, biology is just as based on experimental evidence as is physics.

And right now, there are people with media platforms, people in powerful political positions, who straight-up deny evidence.  They’ll state publicly that the sky is green – and when you provide them with a spectrograph showing a peak at 470 nm, they choose to ignore science and believe what they want to believe.  That’s always been dangerous.  It’s downright deadly in a time of global plague.

So I’m here for a lot of reasons, including a love of physics itself, a love of performance, a love of community (even a virtual community whom I can’t see behind this camera), a love for the relationships I’ve built with students and colleagues through decades of teaching physics… including even that I’m getting paid.  But underlying everything is the hope that I can light a candle in the darkness that is science denialism… to help the next generations of students understand the meaning and power of scientific evidence.

Now, to the physics… today we are discussing angular momentum and its conservation.

31 March 2020

Mail time: What equipment did I use for rotational motion demos?

Edna fan art by @aldescery
On the March 25, 27, and 30 AP Physics 1 youtube review shows, I used some equipment to make angular velocity-vs. time graphs, and to spin my pet hippopotomus Edna around on a rotating  platform.

Julia was one of many physics teachers who asked, where did I obtain the rotating disk (from show #1) and the rotating platform (from show #4)?

Julia and everyone, I'm so glad you're watching!

The Pasco rotary motion sensor can make angular position, velocity, and acceleration vs. time graphs.  I have the new wireless version, which works via bluetooth with my phone or ipad on the free "Sparkvue" app.  That's what I used when I had the two objects connected by a string over a disk.

The rotational platform is a big investment.  When we built our new science building in 2012, I had a nearly blank check to buy equipment - so I bought the Pasco complete rotational system.  Just the base and the disk attachment would be enough.  It's structured so that a Pasco-branded photogate can mount beneath the disk and measure angular velocity rather, um, more elegantly than I did on Monday's show.  But I only have Vernier-brand photgates, which don't fit.

When I did my open lab for teachers a few years back, we spent a few hours taking a trip to the hardware store to create the $5 version of this rotation system.  Get some 1/2 inch PVC pipe and two 90-degree attacher joints.*  Make a "T" out of the PVC.  Place the bottom part of the T over top of a securely-mounted ringstand... the top of the T will rotate pretty cleanly.  You can wind a string around the PVC to provide a torque, just like I did on Monday's show!

*Can you tell from the language use here that I have no skills with hardware? 

29 March 2020

Official AP Physics 1 Review Show - Monday Mar 30, noon EDT, N2L for rotation

Edna, my pet hippopotamus, takes a ride as we prepare for Monday's show:

Josh Beck and I are creating AP Physics 1 review shows every weekday at noon eastern time.  These are available live or on demand at the Advanced Placement youtube channel.

While the schedule will be announced a few days in advance of each show, here's what we've done so far:

Mar. 25: Greg, rotational kinematics
Mar. 26: Josh, torque in equilibrium
Mar. 27: Greg, experimental design based on torque in equilibrium

And here's what's on tap next week:

Mar. 30: Greg, Newton's second law for rotation
Mar. 31: Josh, connecting linear and angular speed
Apr. 1: Josh, rotational kinetic energy
Apr. 2: Greg, angular momentum
Apr. 3: Greg, equilibrium of forces

The advantage of watching live is that you can join the community via @JacobsPhysics on twitter; you can even submit questions for me to answer during the show.

26 March 2020

March 2020 AP exam updates - *we don't know* about format.

Hi everybody!  Hope you've been tuning in to me and Josh Beck on the Advanced Placement Youtube Channel.  We'll have a show for you every weekday at noon eastern, at least until exam time.

I'm posting here because I keep hearing incorrect and speculative statements about the 2020 AP exams.  Be just as careful about AP misinformation as you are about COVID misinformation.  Okay, maybe not quite as careful...

What is known:

1. The AP exams will in fact exist for 2020.
2. They will be taken from home, electronically.
3. They will be 45 minutes long.
4. They will not include straight-up multiple choice questions.
5. If you or someone you know needs help with connectivity for the exam, go to

That's it.  Everything else you might have heard is false or unconfirmed as of March.  Further announcements will come on April 3.

What is the format of the questions?  How will answers be input?  No one knows.

The development committees are working quite actively to figure out the answers to these questions.  I don't know how, or how well, any of this will work.  The College Board and ETS are trying very hard to adapt to a New World Order.  Compromises will be made.  It won't be perfect.  But I do trust the people on the development committees to do the absolute best that they can to create a good exam.

Please don't speculate.  Please don't spread rumors; if a student starts a sentence with "I heard that..." please gently end the conversation.  And I'd end it with the following:

The AP Physics test, in any format, tests a student's ability to communicate an understanding of physics principles.  If you know your physics, you'll do fine... no matter the format.

The AP exam cannot ever be "gamed".  If you're trying to find the One Weird Trick that will get credit on a certain style of problem, then, well, you're doomed.

Just practice the same kinds of questions we've always practiced in our courses.  That's all you can do, anyway.


22 March 2020

2020 AP updates, and I'll be doing AP Physics 1 review classes for the College Board...

Folks, as the Horsemen ride, massive changes are happening in the world of AP Physics.  Take a look here for official announcements.  (I really hope that this link goes inactive someday in the future... someday when we can again congregate in public.)

The quick summary for AP Physics 1 in 2020 only:

* Testing will be available online from home.
* Electricity, circuits, and waves will NOT be on the exam.
* The AP reading will done online.

A lotta more details are available on the announcement page.  And I've no doubt even more details will show up in the next few weeks.

Online review, hosted by Greg!

The College Board has tapped a bunch of folks to do a set of online review classes in every discipline.  For AP Physics 1, your hosts are: North Carolina's Josh Beck, and me.

Starting Wednesday March 25, and continuing through at least the end of April, Josh or I will be on live at noon eastern time via the Advanced Placement Youtube Channel.  The sessions will be available asynchronously* as well as live. 

*There's a word that I may have seen like thrice in my life before last week, and now it's part of my daily vocabulary 

We're still working out the topics for each session.  These will be posted on the channel. 

I'll be broadcasting alone from my classroom - I live on campus at my boarding school, where the classrooms are sanitized, private to each teacher, and for now open for business.  That means that I have access to my equipment.  For example, the March 25 class will be about rotational kinematics.  I've got quantitative demonstrations set up with a PASCO wireless rotational motion probe.  Friday I'll be doing a class about experimental design, focusing on torque in equilibrium - again, with live demonstrations.

If you have thoughts or suggestions or comments, please contact me via twitter - I'm @gregcjacobs, though for students during the live sessions I'm going to try using @JacobsPhysics.  We'll see how that all goes. 

Remember, we're all new to this world of exclusively online interaction.  Expect my classes to be raw - fun, engaging, but not a polished television show.  I'll screw up on air.  That's okay.  It's authentic.

19 March 2020

Jacobs Physics Podcast: Season 3, episode 2: AP Physics 1 2019 problem 2, the modified atwood machine

Today we discuss the Quantitative-Qualitative Translation question from the 2019 AP Physics 1 exam.  Digressions include:

* How to practice limiting case reasoning

* Two different approaches to two-body problems, with pedagogical advantages/disadvantages of each

* Why "derive" doesn't mean "show your work," it means "communicate using mathematics"

* Credit for being wrong but consistent (with good physics)

Tune in via this link.  The podcast is 31 minutes long.  The first 28 minutes discuss the rubric, but in concert with a thorough discussion of the underlying physics, the philosophy of teaching these topics, and the philosophy of awarding (or not awarding) the points described in the rubric.  If you're just looking for an executive summary of how the points were awarded, fast forward to the 28-minute mark.

16 March 2020

Physics teaching in the time of COVID-19

If you’re from the future reading this - either as part of a historical investigation into the education industry, or perhaps as documentation of the End Times - know that schools across the USA are closed for at least the next few weeks.  It is not at all clear when we will open back up.  Many of us are being asked, encouraged, or allowed to run activities online.  

I am, in fact, going to use online platforms to work with my classes.  I’ll give details in a moment.  But first, let’s discuss what’s important.

I have repeatedly made the analogy between learning physics, and playing a sport.  I consciously treat my class as a team whose goal is to learn physics collaboratively, under my guidance as coach.  I think of tests and exams the same way as coaches think of games and meets.  The AP exam (or, in conceptual physics, the thesis-defense-style Physics Fights at year’s end) compare to the state championship events.  

We have a shared understanding as a society about the importance of sports.  Sports are an end unto themselves - we care deeply about winning or losing.  And, sports are a means to an end - for example, the physical fitness habits, the social skills of winning humbly and losing graciously, serve us well beyond this year’s season.

Yet when life interferes with sport, we all understand that life takes precedence.  Sport is meaningless in the shadow of War, Famine, Pestilence, and Death.

Right now, Pestilence (and in some cases even Death) have intruded on our school year.  That means we and our students must acknowledge different priorities.  That means physics simply is not important right now.

We should not, can not, talk about how to “hold students accountable for learning.”  We should not be judging students in any way for their participation or lack thereof in our online classes.  I think most teachers are aware how some students might not have strong internet connections at home, and so will have a hard time keeping up, or that some students may themselves be sick.  But are we thinking about the students who are being asked to perform child care, or grandparent care?  Are we thinking about the student whose parent has a fever, and can’t even know whether it’s The Disease or not?  Or even the healthy student listening to their parents worry out loud about jobs and health and income and quarantine… How can such students focus on physics?  Why should they even be given the guilt trip of being asked to focus on physics at all?

But Greg, you said you are going to hold online classes.

Yes.  Because plenty of my students will welcome the diversion of physics class.  They will want the semblance of normality that my class’s time together brings to them.  They will want (virtual) human contact with their classmates, their teammates.  They will want an intellectual escape from family burdens, from worry, from fear.  I will be there for those students who want me to be there.

Principles of my approach to online course delivery during the COVID crisis.

I’m going to continue teaching like a video game.  I’ll provide a list of problems / activities.  I’ll check student work - live via videochat, or via email - so that students can either move on or try again.  Advancement along the list will hopefully feel like “leveling up.”  

I will do everything in my power to avoid assigning grades.  Or to avoid anything that could be perceived by a student as shame or guilt for failure.  Yeah, I know some of us will be required to submit grades - well, then I’d be submitting A’s for all.  Phthphth.  See above, about what’s important right now.

My school is going to create some sort of schedule, so that I can do live online class.  I’ll try to hold as much of a normal class as possible: starting with a “quiz” (i.e. a common set of questions that we all respond to individually, then find out the solutions together), then taking questions on any topic, then working on “come and show me” problems and activities.  They’ll have to show me electronically, they’ll have to collaborate via text or private videochat… my hope is that for those who attend, just being together virtually can provide comfort, human contact, and perhaps a wee sense of normalcy or purpose.

I will focus on medium-term goals.  For my AP class, I have two goals:

(1) In the Pivot Interactives video of a marble colliding with the wooden block, I ask: is linear momentum conserved?  Angular momentum? Mechanical energy?  I’ll have interested students prepare a 2 minute presentation on one of these questions.  Then, I’ll have a veteran of my class serve as “examiner” in a physics fight, asking five minutes’ worth of questions.  If I’m lucky, I’ll be able to arrange for incoming students and their parents to serve as an audience.  This will hopefully happen the first weekend of April.

(2) Continue working toward the AP Physics 1 exam in May.  These folks have worked hard all year, and most could pass the exam today with no further effort.  Most of my class will want to continue preparing, the same way a sports team would want to keep practicing for the state championship.  So, we’ll keep physics fresh in everyone’s mind, we’ll do problems and experiments together.  I’ll suggest activities designed around Pivot Interactives and The Physics Aviary and The Physics Classroom.  We’ll do old AP questions, and score them together.  We took an AP practice exam on March 5 - I’m sending a corrections packet out via mail, so they can re-try the problems they missed (and they can show me via videochat or email for feedback).

For my conceptual class, I have one major goal: the May 17 tournament of physics fights.  In a normal year, students work from late April in groups led by AP students to prepare two college-level investigations.  This year, I’ll offer to help students learn about momentum and energy - not because they’ll be tested on this material, but because their work will help them in May when it’s physics fight time.  (Students are asked to choose two of three possible problems for the physics fights.  Only one of them involves momentum and energy, so even students who stay completely away from online study will be able to participate effectively in physics fights upon our return.)

Most importantly, I will adapt as things work or don’t work.  I have no idea how a month of online-only gatherings will go.  I’ll listen to students, try new things, find out what students figure out on their own to be more useful than my online “teaching.”  I’ll be supportive in every possible way of those students who are absent or unengaged - nothing is required.

If that means a student doesn’t want to do physics, but instead wants to tell me about the non-physics aspects of their life under the shadow of a pandemic, well, it’s my job to listen.  Literally.  We are called to “know, challenge, and love” our students.  Right now most of them have plenty of challenge in their lives, so I’ve got to focus on the knowing and the loving.

14 March 2020

Jacobs Physics Podcast: Season 3, episode 1, 2019 AP Physics 1 problem 1

I've no doubt that many folks are looking for good online AP Physics review.  Well, I'm going to go through the entire AP Physics 1 exam from 2019 on a series of 30 minute podcasts.  Today, I start with problem 1: velocity-time graph and change in angular momentum for blocks on a table.  Digressions include:

* The five facts you need to know about velocity-time graphs (and you don't need to know anything else!  Really!

* My one-day approach to teaching velocity-time graphs, including experimental work

* Why you should never ask (or answer) questions during a practice AP test, or really during any test or quiz

* How to set up this problem experimentally

* When and whether you need to worry about drawing arrows at the right spot and to the right length on a free body diagram.

If you have other questions, stories, or comments about the Jacobs Physics Podcasts, please email, or post a comment here.  I'm happy to take requests for future problems to discuss!  (Send me a few hundred dollars cash, and I'll probably even record a podcast on the exact problem you're working on right now.  :-)  )

Here's the link to this season's episode 1, about the 2019 AP Physics 1 problem 1.  You might, um, notice that I called it season 4 in the opening.  Sorry.  It's season 3.

To get other Jacobs Physics Podcast episodes, go here and here and here and here and here and here.  (Or just type "podcast" in the search box.)

12 March 2020

Design: How do we convey basic information to students?

Today's post is part of a series discussing how educational design is, or is not, or can be adapted to the humanity of the end-user.  See the introductory post here.

I’m asked at institutes, how do I give students notes?  Well, I don’t.  I've been too frustrated on the user end by the whole concept of "notes".  

See, in fifth grade, I was taught to watch a teacher write information on a chalk board, then to copy everything she wrote into a notebook.  This was an important skill… in CE 1100, when transcription-by-monk was the only available alternative to the Xerox machine.

In seventh grade, I was required to make notes of what the teacher had said orally in class - with express hints like “now write this down.” This was an important skill… in the days when the teacher was the sole font of information.

Even thirty years ago, information was hard to come by.  Students had textbooks, and they were the primary and authoritative source of information.  Libraries were available to some, but even a great college library required significant effort in order to find useful references - in any subject.  The added value of a good teacher then was that the teacher had (presumably) read and investigated references beyond just the textbook, and so could deliver context and deeper knowledge through lecture.  The prize, as our headmaster stated in his first ever address to the faculty, went to the people who learned the most information.

Now, information is trivially easy to come by.  Yeah, yeah, no one can learn physics just from a bunch of wikipedia pages, but really, that’s just as useful in isolation as the old-style textbook was.  Enough good content is available (again, in any subject) for an interested student to find out whatever information they want.  The prize nowadays goes to the people who can:

     (1) sort good information from bad
     (2) assimilate what’s relevant and ignore what’s not
     (3) construct useful stories from the glut of plentiful information.

How, then, do we convey basic information to students in the most user-friendly way, while helping students with these three goals?  

Don’t be thinking in terms of what students “need for college.”  Yes, I know, some college professors require students to read antiquated textbooks, or to listen to boring lectures with badly-constructed powerpoint slides.  That doesn’t mean you should follow suit.  On one hand, you shouldn’t use ineffective pedagogy with which students are generally uncooperative merely because other teachers do - I mean, if a bunch of college professors all jumped off a bridge, would you?  But more than that, you do your student far more of a service if you show them *effective* pedagogy that they can fall back on for themselves when their future teachers are useless.  Teach them how to learn physics in a way that works for them.  You’ll find that your students become adaptable to any professor.

But, how do I “give notes?"  Think of the minimum information that students need to know RIGHT NOW, for today’s topic.  That’s what my fact sheets are for - I’ve already filtered dense textbook pages down to just the most necessary facts.  I hand out a hard copy of the day’s new facts.

Then, I have students use these facts in context.  It’s tough to memorize six different facts about velocity-time graphs.  It become easy when the class has spent an hour-long class period writing them down as they apply to different creative lab exercises.

Finally, I give regular quizzes on these facts.  Not as a “gotcha” game, but as a reminder, as a way of learning the facts through repetition and use.  These quizzes are just as effective without them “counting” in a grade book.  Give the quizzes, “grade” them, put a score on them, collect them.  If someone is consistently stinking up the joint, have them come in to redo some until they do better.  That’s good enough.  Your students will have enough background to spend most of their physics time engaged in interesting lab work and problem solving.

08 March 2020

Design: Eliminating no-name papers

Today's post is part of a series discussing how educational design is, or is not, or can be adapted to the humanity of the end-user.  See the introductory post here.

Possibly the simplest example of end-user design that I've personally undertaken in the classroom:  I was annoyed, as so many teachers are, that students turn in papers without their name on them.  What to do?

You can, as I tried one year, take points off for "no name".  What happened?

(a) Students got angry.  They didn't see the big deal.  (They also didn't have the perspective that five no-name papers in a stack of 60 caused a significant time sink for me.)  The student-teacher relationship frayed - students who already resented that I had power over them, power they only sort-of consented to, felt that I was asserting that power inappropriately and irrationally.

(b) The frequency of no-name papers did not improve.  (Students don't care about points and grades the way most teachers think they do or should.)

Once I observed (b), then my hand was forced: to continue to take off points for no name papers, knowing that the consequence did not have any effect on the issue I was trying to solve, would constitute malpractice in educational design.  It would be using the power granted to me in the classroom to shame students for being, well, people.  People as they are, not people as I want them to be.

This was the genesis of collecting assignments seat-to-seat.  Now, every paper I hand out includes a header at the top saying "Name:________________.  I collect assignments at the beginning of class while students are working on the daily quiz.  The prompt at the top of the page generally is enough of a reminder such that students write their names.  However, I also developed the habit of checking for a name as I pick up the paper.  It's straightforward to whisper - without exasperation or sarcasm - "Mr. Williams, could you please write your name here?"  And Mr. Williams does so quickly, because he wants to get back to the quiz.  Often he mouths a quick apology.  No shame.  No anger.  No strained relationship.

As I mention in the linked post, collecting assignments seat-to-seat has other benefits that address the reality of how students behave.  In particular, I know that even quite honest teenagers will not easily volunteer the fact that they did not finish an assignment.  (They generally won't lie right to a teacher's face, but they will take pains to make the teacher less likely to notice - like they'll bury a half-done assignment near the bottom of a stack.)  Collecting seat-to-seat doesn't provide the opportunity to hide.

07 March 2020

Design Revolution: the students are not the problem.

I don't know what it says about me that I'm reading books recommended by comedic soccer podcasters... but I'm reading User Friendly: How the Hidden Rules of Design Are Changing the Way We Live, Work, and Play by Cliff Kuang, as recommended on the Men In Blazers Bald Mart.

The book's thesis isn't novel to me, but the anecdotes within are.  The opening chapter is an account of the Three Mile Island incident that killed the American nuclear industry.  Kuang doesn't see operator error, though highly trained, expert operators did make errors.  He sees design error.  No reasonable person, trained or not, could possibly make sense of the 1979-era control panels with multicolored lights (different colors meaning many different things), buttons which lit when pressed even if the function ascribed to the button didn't occur, gauges in inaccessible spots requiring contortions to read.  

Similarly, Kuang delved into World War 2 plane crashes, most of which were attributed to "pilot error."  Once again, he takes issue with design, not with the people using the design.  For example, why would levers for landing gear and wing flaps be essentially indistinguishable?  Kuang cited over 400 B-17 crashes that occurred because pilots failed to deploy landing gear in an otherwise unremarkable runway approach - they twiddled the wrong identical lever, and didn't notice the mistake until it was too late.

In these and other cases, designers - and those executives making big-picture decisions about designs - exhibited what to me borders on criminal arrogance.  Why can't the idiot pilots just remember which lever to pull?  The plant operators need to RTFM.*  Let's schedule another mandatory monthly 6-hour training session so they'll stop screwing up.

* Read The Fission Manual, I think.

Does this attitude sound familiar?  If not, head down to a faculty table in the lunchroom.  Or, just as disturbingly, listen in on a meeting of school administrators discussing the failings of teachers.

Kuang's thesis is that the most useful advances in technology have come when designers have considered the humanity of the end users: not treating people as they should be, but treating people as they are.  People don't read the manual.  People push random buttons accidentally, or out of panic.  People don't remember important details in the critical moment - when in a hurry or stressed, their recall grows worse.  People react illogically and emotionally even to logical and dispassionate stiumli.

What innovations have you made in your classroom to adapt to teenagers as they are, not as we want them to be?

I've spent a quarter-century adapting my teaching to the end user, doing what seems to work rather than just what everyone says should work.  Yes, learning physics requires significant effort and engagement on the part of the student.  It's my job to help the student figure out just what sorts of effort and engagement lead to success.  It's my job to create a class culture and atmosphere that encourages useful kinds of effort and engagement.  

If Kuang is right, it's my job to optimize the design of my class for students who can and will be inconsistently attentive, emotionally prickly, unlikely to read directions... in other words, to optimize for my teenaged students, in all their humanity.  That takes enormous effort on my part.  It requires trial and error.  It requires me to be my own worst critic, asking myself regularly: is there a better way?

The next several posts will discuss adapting teaching to the humanity of the end user.  I'll tell stories of design ideas that worked or didn't work.  

My purpose is to revolutionize physics teachers' thinking, in the same way that the iphone revolutionized the entire technology design industry.  

(Oh, and the design revolution I have in mind extends as well to educational administration.  I am called to design and re-design my classes round what is in actuality effective for my non-ideal students.  Administrators should feel similarly called to design faculty meetings, development/evaluation programs, and all administration-teacher relationships around what is most effective for supporting teachers - in all their human foibles.)

04 March 2020

I'm a "Come and Show Me" teacher.

I'm not a Sit-and-Listen teacher.  That doesn't I never talk at students from the front of the room.  My class grades daily quizzes together, while I explain the solutions.  Occasionally in the AP class - probably once per week early in the year, though essentially never in conceptual physics - I do a quantitative demonstration from the front of the room.  But that's it.

After the daily quiz, I give students a list of things to do, usually involving prediction and measurement in the laboratory.  Sometimes the list includes test or quiz corrections.  Sometimes a Pivot Interactives video or a The Physics Classroom concept builder make the list.  

Whatever the activity, students are released quickly from the responsibility of paying attention to the person in front of the room.  That's more important than the majority of teachers realize.  See, you get antsy sitting through an hour-long faculty meeting - you consider a three-hour district professional development presentation your personal purgatory.*  How do you think students feel as they are shuttled among seven different sit-and-listen classes with minimal breaks in between?  And they do this every single day?

*The sale of indulgences would create a significant revenue stream.**

**Shh, Greg, don't give anyone ideas, dangit.

Okay, many physics teachers do in fact leave plenty of time for their students to work independently on some of the tasks I've described above.  What do you do while they work?

Some teachers walk through the room giving advice, encouraging questions, helping to debug lab equipment.  That's fine.  I know some amazing teachers who are always on their feet through the room.

I don't walk.  I sit at the front of the room.  Students are asked to bring me their work after each problem, after they have acquired data, when they've reached a defined check point.  

At last week's AP workshop, Glenn experienced my position-time graph exercise. "Oh, so you're a Come and Show Me Teacher," Glenn told me.  Yes, yes I am!  I had never heard that term, but I love it.  

The advantages of Come and Show Me go beyond merely avoiding student ennui.  Students physically moving around changes the dynamic of the class.  It makes the atmosphere far more similar to a coffee shop than a library.  And where do students generally choose to work these days?  The Panera in University City, Philadelphia on Friday afternoon was chock full of students studying, to the extent that a seat was hard to find.  I wonder ironically whether the UPenn Library was similarly packed...

The Come and Show Me class style encourages students to talk to each other about physics - since I'm not within easy earshot of each student, and since I've generally got a line of people waiting to talk to me, it's much more effective to ask a friend rather than me if a student has a quick question.  Come and Show Me avoids noble-yet-fruitless staring at problems without making progress, or charging though a problem for most of an hour compounding mistake upon mistake.  Instead of finding out later that their approach was all wrong (and then being frustrated with the wasted time that can't come back), students get feedback sooner rather than later.  But Come and Show Me explicitly discourages students from relying on me to answer every little question, to do all the heavy lifting for them.  Just the obstacle of having to get up and walk to my desk, then to stand in line for a minute or two, encourages everyone to work out whatever they can for themselves.

To use this style of teaching every day requires significant culture building early in the year, a large and diverse set of exercises for students that include things to come and show me... and enormous confidence on the part of the teacher.  Confidence that the class, for the most part, will adapt to this very different approach to learning.  Confidence that when a couple of students don't adapt, your style is still serving the vast majority of the class well.  Confidence that when you hear passive-aggressive comments from parents and colleagues ("You didn't go over this, I don't know how anyone is supposed to understand." is the most common), you should nevertheless carry on. 

Don't listen to early feedback.  Listen to what people say at year's end, and especially to what they say 1-5 years later.  

What I hear years later is that my students don't remember every detail of each of Newton's laws.  But they do remember how they felt in class - they looked forward to my class.  They remember the relaxed and friendly atmosphere.  They remember their pride when they finished each listed item and moved on to the next.  And they remember that there was no room for BS, no room for half-measures in solving physics problems: since they had to show me their work right then, in person, with a line of people behind them... they were careful to put forth truly their best effort. 

19 February 2020

How do I convince my students to sign up for both AP Physics C mechanics and E&M?

On the "Pretty Good Physics" teacher message board - yes, sorry, you must be a teacher to join - a teacher asked how to approach the new signup process for AP exams.  Starting in 2019-20, students must sign up by November (for a full-year course) in order to take the exam.  It's February now, so I know this seems out of date. I think it's worth thinking about now that the October panic of "aargh, should I sign up or not!!!?!" has subsided.

A teacher teaches both AP Physics C mechanics AND E&M.  Completion of the exam is required in order for her students to earn a GPA boost on their transcript.  "Because of the cost," in the past she's allowed students to take either or both exams - even though she covered material and assigned work for both tests in the spring.  But back then, students could decide last-minute whether to pay and sit for the exams.

This year, this teacher worried.  Since students had to register by November... what if they are too scared to sign up for E&M, even if she knows they'll do well?  Even worse, what if the students conspire - "let's sign up for only mechanics, 'cause then we can make teacher skip E&M entirely because none of us signed up!"

She said she needs a plan of what to say to convince students to sign up for E&M - something that's not just "E&M is good for you, it was my favorite course, it'll be yours, too!"

The correspondent is so right, that students are generally risk-averse.  Suggestions about what the teacher personally likes, or what is good for the students, tend to fall on deaf ears - as she suspects.

For those who are teaching APC as a second-year course, I'd suggest following this sequence, teaching algebra-based E&M first, proceeding to calculus-based mechanics, and finishing with calculus-based E&M.  That will start removing the fear of a subject students haven't even seen.  And, this will allay the particular worry that students might try to emotionally blackmail the teacher into not teaching E&M with the whine, "but no one signed up for it!"

I don't like using transactional reasoning, but here it will likely be effective - "We're doing E&M regardless of what you sign up for, so you're being evaluated on that material anyway.  You can only get the GPA and transcript bonus if you sign up.  And I expect that you will do well."  After all, to me the fundamental reason to teach AP is to give students an initial transactional reason to engage.  By the end of the course, they develop a love for physics, an understanding of physics as an end in itself rather than a means to an end.  Yet AP gives us cover while we build expectations and skills in a difficult course - bear with me, because you'll get an extra 0.5 on your GPA and boost your chances of getting into the special college that lets your parents brag to their friends.

Finally, as to the cost of the exam... what do credit hours at a university cost, even a public university?  More than the $94 that an AP exam costs.  Much, much more.  The cost argument is a straw-person.  I mean, obviously it's foolhardy for students to waste money on an exam they won't pass, but isn't the whole point of our teaching to boost the probability that they will pass?  Isn't it the student's job to work hard to make sure they can pass?  If most of the class is failing - which, I must emphatically point out, was NOT the case for this particular correspondent - then something systemic is wrong with the teacher, the students, or the school structure that set everyone up for failure.

There is one possible loophole you might use... Mechanics and E&M are separate courses.  The College Board requires sign-up for full-year and fall-semester courses by November.  However, if your school lists E&M as a second-semester-only course - as on a block schedule - then the sign-up deadline is later.  Talk to your AP coordinator and school registrar if you need to try this.

Most likely, your students will grumble and complain about the early sign-up.  Then they'll just sign up for both exams.  Then they'll be that much more focused on learning all of the content, knowing they're locked in to both exams, that they don't have an out in the spring of their senior year.  Then they'll do well, earn college credit, and be grateful they didn't wimp out.  Sure, there might be a couple of students who don't pass the E&M exam; but they will be far outweighed by those who appreciate your dedication to them, your caring preparation for their college physics weed-out class that they'd otherwise take in a 300-person impersonal lecture hall.