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17 December 2017

Do I enjoy giving exams? Yes.

The question was once asked of me, in a most appropriate manner, whether teachers enjoy giving exams.  The asker seemed brain-dead from his first night of studying, knowing that he had a full week of hard academic work in front of him.

Though he was too polite to verbalize the expression in his face, I suspect his deeper thought was: “Why do teachers put us through this heck of cramming?  Do they get sadistic pleasure out of it?  Do they enjoy tormenting their students?  Weren’t they students once?  WHY DO THEY DO THIS TO US?”

Since the questioner was so polite, since he truly seemed curious about the answer, and since I’m sure much of the student body asks themselves the same question three times* each year, I think the question deserves an answer.  I can’t speak for teachers in general, nor even for teachers at my school.  But I’ll answer for myself:

* my school is on trimesters, not semesters

Yes, I enjoy giving exams, despite the enormous amount of work they create for me and for my students.  But probably not for the reasons you might think.  Put yourself in a teacher’s loafers for a moment…

When exam day arrives, I have dedicated the previous eleven weeks of my life to teaching physics.  I am “on duty” virtually nonstop when school is in session, especially in the fall when learning physics is most difficult for my classes.  When I’m not actually in class teaching, I’m grading assignments, preparing lectures and demonstrations, writing problems and assignments, helping students… You can ask my wife – all trimester I am thoroughly, monkishly, devoted to helping my students learn physics to the best of their ability.

The exam is an opportunity to find out how well I’ve done teaching, and how well my students have done learning.  I want to know – did those long hours, those occasional interminable days and early mornings, did they pay off?  Did I really succeed in develop every student's physics skills?  What can I do better?  What can THEY do better?  What did we do well? 

I think of my teaching job much like a coach’s job.  Did Mr. Hale enjoy the state cross-country meet?  Well, of course he did.  Even though it was the runners who performed, not the coach, Mr. Hale still saw the fruits of his team’s months-long labor in the “final exam”  of the year’s last race.  As in every season, he rejoiced not only for the runners who placed near the top of the league, but also for those who showed dramatic improvement under his tutelage. 

In my class, then, the trimester exam is equivalent to the biggest game of the season.  I am cheering for everyone to do well.  I know from experience that most students, in fact, will do well.  I'm ready to use the exam as a learning tool for those who don't do well - as a learning tool for that student, and as a learning tool for me as I figure out how to help that student do better next time.  

Do I enjoy a student's poor performance?  No.  Yet I thoroughly enjoy the successes, which vastly outnumber the failures; and even when students don't do well, I enjoy the process of finding out how good I and my students have been.

Now let me throw this question back at the student who asked it.  Do you enjoy the state cross country meet?  Because if you don't work really, really hard during the season, you're not likely to win the race.  Even if you do practice well, a freak trip-and-fall could wreck the performance that you've worked all season to produce.  And you could lose not because you didn't work hard, but just because another runner has more natural, raw talent than you do.  YOU COULD FAIL.

So, grasshopper: 

When you feel the same nervous, excited anticipation for your final exam as for the state championship... 

When you develop the same discipline in academics and in sport to prepare every day throughout the season, not just the night before...

When your hope for success overwhelms your fear of failure... 

...then you, too, will enjoy exams.



15 December 2017

A guide for useful and successful semester exams

A school community too often anticipates semester exams as they would an auto-da-fé.  We teachers know that the purpose of exams is not to torture, but to provide a touchstone in the learning process.  When the semester exam process is executed* well, students derive confidence from the skills they demonstrate, providing a foundation for an increased pace and difficulty in the second half of the year. 

*hah!

It’s part of our job, though, to help the students develop an exam-positive view of the learning process.  Our attitude going in, as well as the specific things we ask our students to do in preparation for the exam, must be in line with the true purpose of exams.

Here, then, are four ideas for setting the right tone so that you get the most out of your semester exam.

(1) Insist on serious attention to every assignment throughout the year, so that the exam doesn’t seem like the teacher playing “gotcha”.

Your goal should be to have your students ready for the exam without any extra studying.  Hold every student accountable for not just doing each assignment to get it done, but for doing it right.  When students miss something important on a homework problem, give a similar question on an upcoming quiz.  Require the student who bombs this follow-up quiz to attend an extra-help session to do the problem right.  Make it more trouble to do assigned problems wrong than to do them right.

Why? Ask yourself, what does effective studying for an exam look like?  Very much like the process above.

(2) Be careful not to study-shame

How does this sound from the director of the school play with opening night imminent: “Make sure you practice your scenes 100 times each tonight; those of you who do might hit all your cues, but if you don’t spend that time tonight, your performance will suffer and you’ll trip and fall during the dance number in act 1.”

Even if you don’t intend to shame or threaten your students, that’s what they hear when a teacher explicitly invokes the consequences of unpreparedness.  

Recognize that students - especially juniors and seniors - will not change their exam preparation habits based on entreaties from you.  You think that the student who hasn’t done serious preparation for an exam in any of five classes and two semesters per year for four years will suddenly say “Oh, Mrs. Lipshutz says it’s extra-important to study for physics, I’d better do that.”?!?  If our mere words have that much influence over recalcitrant teenagers, we should be in politics or marketing, not teaching.

More likely, we lose political capital and put emotional distance between us and our students.  Teenagers don’t like to be told what to do, even if what they’re being told is undoubtedly in their self-interest.  They tend to rebel.  There’s no point in complaining about this aspect of teen psychology; we might as well kvetch about how the Bengals always punt on 4th and short.  We’re right, but powerless in the face of human irrationality.  


(3) Use positive rather than negative incentive to promote exam preparation.

Fear of failure is a serious obstacle to success, whether on this particular exam or in physics generally.  

If you give students no direction for exam prep, they will default to study modes that have been successful for them in the past* in math and history courses -- memorize as many facts from the textbook as possible, practice and memorize algorithms that they’ve used in class before.  Such approaches to preparing to do physics are not even wrong - they are actively detrimental to a student’s progress, and to the progress of the class as a whole.  Diligent students who already struggle with difficult concepts undertake their not-even-wrong study regime, bomb the exam, then have ammunition when they tell parents and administrators how your course is too hard and unfair - they studied so much, and still didn’t do well.

* Or at least, modes that parents and teachers believe on faith to be successful       
                                                                                                                                                                   
I’ve found success giving students something straightforward and useful to do for exam preparation. 

“Here is a review exercise consisting of twenty multiple choice questions.  Please fill out the answer sheet on your own, without assistance from anyone - no questions at all, just like on the exam.”*

*(If you can’t trust students to answer these questions on their own, give time in class to do them.  It will be well worth the effort.)  

“Once you’ve answered all the questions, I’ll scan your form.  Extra credit will be awarded to anyone who writes out a thorough justification for all of the problems that they missed.  

"Collaboration with me and classmates on these justifications is encouraged.

“I’m offering a study session after school on Wednesday.  Pizza and nachos will be available.  Come on by – it’ll be fun, and I’ll help you with any questions that are still confusing you.”  

Look what’s accomplished by this approach.

Instead of requiring that students take a practice exam, instead of lecturing about how good an idea it’d be to take a practice exam, you’re couching the practice exam as an optional “extra credit” exercise.   Which approach do you think gets more willing cooperation?  Yeah, I don’t believe in extra credit, either, but I *do* believe in students undertaking exam preparation enthusiastically rather than reluctantly.  (And students who didn’t complete the practice have no standing for a post-exam complaint to parents and administrators - wait, you “studied for hours” but you didn’t do a small practice assignment for extra credit?  Not likely.)

You focus the students on what they really need to study, because they spend most of their time correcting the questions they missed.  Without such guidance, students may spend a couple of hours doing problem types they already are good at, while ignoring the topics or styles of problem on which they struggled. 

Some students will work themselves into a panic, thinking there’s always more that can and should be done to prepare for an exam.  These students are put at their ease: “Once you finish this exercise, you are ready.  There’s nothing more you should or can do to prepare.”

Some students will tend to do nothing at all in preparation for the exam, even though a review of some sort would be useful for them.  These folks will tend to do an extra credit exercise that all their classmates are doing, too - just to be social, if nothing else. And lo, your recalcitrant students have studied, without even a nanopascal of pressure from the teacher.

(4) Make the exam itself – and the follow-up to the exam – worthy of your class goals.

But that’s an article for a different time…







06 December 2017

Don't play cops and robbers with phones.

In a September post, I explained briefly how I deal with students who ask to go to the bathroom.  It's very simple: I say, please don't ask, just place your phone on your desk and go. 

The comment section of that post became active, and brought up an important piece of teaching philosophy.  First, here's my follow-up comment explaining the purpose behind the "just put your phone down and go" approach:

Note that I'm not in any way making the rule "no texting in the bathroom!" Uh-uh. That sounds condescending, it gives students ideas, and it worries the rule-followers. 
No rules here, in fact I'm giving students freedom from rules - in other classes, they feel oppressed that they have to ask permission to exercise a simple bodily function, and furthermore that the teacher is likely to nag them about their body's timing. Here, they are free to do as they need to. 
Yet, trust but verify. Since the phone goes on the desk as a matter routine (not rule), there won't be any texting in the bathroom. Then it's my job to hold activities interesting enough to minimize using the bathroom as an excuse to relieve the boredom of class.

Later on, Dean Baird brought up how students will, inevitably and frustratingly, escalate a battle with their teacher passive-aggressively:

Seems reasonable. Of course, students intent on "phoning out" while using the hall pass will equip themselves with "burners" to satisfy instructors who adopt such strategies. Hall pass use is a sticky wicket; a puzzle not so easily solved. In courses populated y highly academically challenged students, some find a daily need for hall pass usage. And any kind of restriction is virtually impossible to implement. Offering carrots for non-usage works only with students concerned with academic performance. "Pretty good" and "Good enough" solutions are the best we can realistically hope for.

Dean's right that some students will see bathroom texting as a game, to see how they can beat the system and "stick it to The Man." (True even when The Man is, in fact, The Woman.)

And my response - LET THEM. As soon as we engage as cop, the students engage as robber.

I say "please leave your phone" for the same reason the audience is asked "please turn off your phones" before a stage play begins. It's all too easy for anyone, adult or teenager, to fall to the temptation to real-quick check that important text, or to answer a buzzing phone from a number we recognize. Leaving the phone in the classroom, turning off the phone before the performance eliminates that temptation and helps the class/audience maintain an extended period of focus.

So what do we say about the audience member who smirks and pulls out a second, burner phone on which to text during the play, and then tells the usher "hey, but I did what you said, I turned off my phone, you can't kick me out, I'm gonna sue?" That's a problem that goes beyond techniques to manage people; such behavior is no different from extending a middle finger to everyone, including the performers and the other audience members. This dumbarse needs to be ushered away toot sweet without discussion.

But the existence of the willful fool doesn't mean that we should change our respectful approach to the rest of the audience. "Okay, folks, last night we had a guy texting in the middle of the performance and thumbing his nose at the house rules. I'm sick of you audience people not being able to keep away from your phones. So tonight, we're going to collect phones before the show, and anyone who sneaks out a second phone will face criminal charges. Here's Chief Wiggum at the front ready to enforce those rules. We're not playing around, got it?"

And that's what teachers sound like when they make draconian rules to deal with one or two uncooperative students. The guy using the burner phone in the bathroom thinks he scored a point against you. But we're not keeping score. Find a way to deal with the individual that doesn't involve class rules. Or just ignore him - the rest of the class may laugh with him, but if no one else is using burner phones, maybe it's not that important for Batman to defeat the Bathroom Texter. :-)

04 December 2017

Motion graphs - pay attention to subjects and verbs

The biggest mental block toward understanding motion graphs is the idea of a representation: that features of a graph indicate real motion of a cart.  It takes careful teaching on our part, and mental discipline on our students' parts, to connect the vertical axis value of a velocity-time graph (or the steepness of a position-time graph) to how a cart actually moves. 

The best tool I've discovered to help students make these connections is the written word.  I hand out the facts about motion graphs, and we do my version of a graph-matching exercise.  But students can't just get the answer right and call it a day... they must write their justifications using (a) a fact from the sheet written out word-for-word, and (b) how that fact connects to the graph their working on.

And in this way I can nip faulty reasoning in the bud.  I make them rewrite immediately when they tell me "the cart slows down because the graph says," because there's no fact of physics involved there - even if they're right that the cart slows down. 

More importantly, I pay careful attention to subjects and verbs.  The graph can change steepness; the graph's vertical axis value can change.  The steepness and vertical axis values represent how a cart in the classroom moves.  It's important that no one says "the graph moves" or "the cart's steepness changes."  When I see those statements, I ask the student to rewrite with the correct subject and verb.

Students at first find this nitpicky.  So what.  By now they should (and do) know that physics isn't about right answers, physics is about communicating an understanding of how the world works.  After a few classes, the class is really quite good at interpreting motion graphs, and they stop confusing the features of the representation with the real, live motion of a cart.

The following is a note I sent to my 9th grade class last night as a reminder of the care they must use in their written responses to motion graph questions.

Please consider carefully the subjects and verbs you use on your motion graph justifications.  

"The cart moves closer to zero on the vertical axis, and so slows down" makes no sense.  As you've seen, the cart moves on a track in the classroom; the cart cannot move anywhere "on the vertical axis."

"The graph moves upward on the vertical axis" similarly makes no sense - the graph does not move, the graph is still on the paper on your desk.*

* Unless you threw it upward or something.

The cart moves; the graph does not.  The vertical axis of the graph indicates how fast and which way the cart moves.  

You want to say, "The vertical axis values get closer to zero, so the cart's speed gets closer to zero."

(And you never, ever want to use the word "it."  Write "I didn't say it" on top of your problem set for an extra credit point.  Don't tell others this, keep it to yourself!  :-)  )

24 November 2017

Multiple options for a Physics C multiple choice question about capacitors

A parallel-plate capacitor is filled with air. Each plate has area 10 cm2. The separation between plates is 2.0 cm. The top place stores +200 nC of charge, while the bottom plate stores -200 nC of charge.


Above is just the stem of the question I'm writing for the upcoming edition of 5 Steps to a 5: AP Physics C.  Consider it a "goal-less" problem for a moment.  What could be figured out?



The first and most obvious answer is to calculate the capacitance of the capacitor using C = εA/d.  And yes, that is a calculation fraught with pitfalls, as the plate area and separation have to be converted to SI units.*  But carrying out this sort of calculation is not the point of introductory physics.  If you really want a correct calculation, don't ask a first-year high school student with a calculator - use Wolfram Alpha.  More importantly, I don't expect even strong students to be able to calculate the right answer in about a minute.


* Or I suppose you could convert epsilon-naught to F/cm.  Whatever floats your boat.

Better, more authentic questions might involve semi-quantitative reasoning.  What happens to the capacitance when I double the plate area? Plate separation?  Charge storage?  Using C = εA/d, you can see quickly that the capacitance doubles, halves, or remains the same because the relevant equation is in the numerator, denominator, and not involved, respectively. 

A further step could involve graphs - what would an experimental graph of capacitance vs. plate area, plate separation, or charge storage look like?  Linear, inverse, and horizontal, respectively.

Or, we could go one step beyond single-equation reasoning to ask how the electric potential across the capacitor changes depending on plate area, plate separation, or charge storage.  This question involves combining two fundamental relationships: C = εA/d for the capacitance, and Q = CV for the voltage.  In this case doubling plate area doubles capacitance, but halves voltage; doubling plate separation halves capacitance and doubles voltage; doubling charge storage doesn't change capacitance but doubles voltage.

(And you could even ask about the electric field inside the capacitor, which is uniform and equal to V/d.  Or the field or potential at several positions inside the capacitor.  Or...)

A fun exercise might be to present your class with the stem above and some whiteboards with, say, 10 minutes remaining in class.  Then tomorrow's daily quiz would include two multiple choice questions based on this stem, with only two minutes to answer.  I'll bet you get (a) good conversation amongst the students, (b) mostly right answers on the quiz, and (c) everyone finishing the quiz with lots of time to spare.

16 November 2017

Pivot Interactives - these videos are so worth the money.

Screenshot from Pivot Interactives
As you might have noticed, my all-time favorite internet physics resource Direct Measurement Videos has migrated.

Vernier now is selling access to "Pivot Interactives", for $150 per year or $5 per student, whichever is greater.  On one hand, I wish the National Science Foundation had stepped up with a seven-figure grant for primary DMV creator Peter Bohacek so that he could continue to provide these resources free to physics teachers.  I mean, I can list probably 102 NSF grants that flush my tax money down the toilet. Nevertheless, I'm happy that Vernier has seen the extraordinary value in these exercises to keep them alive.  

The question for the physics teaching community is, then, do we spend the couple hundred beans to get access to Vernier's new site?  For me, the answer is definitely "yes."  

I've made it my official teaching goal this year to replace as many textbook-style homework problems as possible with Pivot exercises.  Since Peter and company have been hard at work adding to their video library, I'm finding this goal easy going.

Take, for example, the car-around-a-traffic-circle problem.  I've always started my circular motion unit there, as it's a situation all my students have experienced.  I ask, how fast can the car go around the curve?  We discover that the maximum speed depends only on the curve's radius, g, and the coefficient of (static) friction. 

Great.  But this is an abstract "imagine if" problem.  I can't take my students to a traffic circle for experimentation - the nearest one is 20 miles away, and is too busy for fooling around, anyway.  All I can do is suggest that the yellow suggested maximum speed signs don't include a mass variable - they say "max 25 mph", not "max speed in mph is 0.025 times the mass of your car in kg."  Interesting... but not experimental.

Well, look at the screenshot at the top of the post.  Peter took his drone to a traffic circle.  He drove the gray car around the circle at a speed that was always on the verge of slipping.  When he imported the video, he included tools to find angles around the circle, the radius of the circle, and a frame-by-frame timer.  I can't do this experiment, but Peter can. And did.

So for a homework problem later in the circular motion unit, I link the class to this Pivot Interactives video.  The site allows me to customize the assignment - the default is quite good, but I can add or eliminate questions and guidance.  For me, I like a clean prompt like "Determine the (maximum) coefficient of static friction between the car's tires and the ground."  The site allows students to input their solution and reasoning directly in the space provided; you can then scroll simply from one response to the net, awarding points if you'd like.  I prefer to have students answer on paper, but that feature seems to work as well (paper not provided by Vernier).

There's so much more that Pivot does.  I prefer the simple open-ended "determine this parameter" exercises.  But Pivot also has some modeling exercises, providing an easy graphing interface that allows students to make and linearize plots.  These multi-layered videos allow you to change multiple parameters.  The prompts guide students through what essentially is a complete lab exercise which you might never be able to do in your own classroom; or, a lab exercise you don't have the time to do in your classroom but can assign for homework.  I know that Vernier has gotten some serious physics teaching experts, including Kelly O'Shea, writing these exercises.  

And Peter is adding videos every time I look.  

Look, I know it's disappointing to have to pay for what had been available for free.  And I generally don't recommend paying for physics content on the internet.  Nevertheless.  

Vernier has hired the varsity for this project.  Everything I see on the site is something that makes me say "wow."  Pivot cannot replace a physics teacher doing active lab work in the classroom, because nothing can.  Using Pivot gets students as close as I believe it is possible to come to an online laboratory experience.  I highly recommend.

GCJ

(Note that Peter and Vernier have not paid me in any way for this endorsement.)

15 November 2017

Umpires, and Training Students to Grade Each Others' Daily Quizzes

The most effective tool I've ever discovered for 9th grade conceptual physics is not the daily quiz - it's the grading of the daily quiz.  Students trade papers, pick up the red pens I provide, and mark right or wrong as I go over each answer.  

The purpose here is pedagogical, not logistical.  I'm perfectly capable of rephrasing these questions as multiple choice for ease of grading; and it's not like I don't have time to grade these simple quizzes, anyway.  No, the reason we trade and grade daily quizzes is that students pay attention to each question threefold:  once when they take the quiz, once to figure out how to grade the quiz in front of them, and once to think about whether they themselves got each question right. 

It's essential, though, to establish an appropriate tone and ground rules in order for trade-and-grade to be successful.  Here are some principles that my class learns that make the daily quizzes work.

(1) We are a team.  Daily quiz performance is just like a football team's conditioning sprints.  Teams have fast and slow players.  Good teammates respect the effort and talent of those who are the fastest; good teammates encourage and respect those who are slower, too.  

The team atmosphere must be established from the first day of school.  The highest form of sin in my class is to denigrate  a classmate for a wrong answer.  Even negative body language directed at another student - a teammate - is unacceptable.  

Because we are a team, we can depersonalize the grading process.  A grader is acting as an umpire for the team.  Umpires don't call people out because they dislike the players, they call safe or out honestly based on their judgment, and on a shared respect for the game.  A good team doesn't want a biased umpire, even if the bias is in their favor - they want to win or lose with integrity.  Those who play sports know that a tainted win is nothing to be proud of. 

(2) Don't look at or talk to the person grading your paper.  You have enough to focus on with the paper you are grading.  Trust your classmate to evaluate your work appropriately.  No one respects the player who continually tells the umpires how to do their job.

(3) Don't talk to the person whose paper you're grading.  Imagine an umpire who, presented with a close pitch, asks the catcher: "Hey, did you mean for that pitch to be over the outside corner?"  The batter would go berserk!  So students should never ask "hey, did you mean this line to be straight?"  If you can't tell, mark it wrong.  The burden is on the student writing the quiz to communicate clearly.  

(In my AP classes, I ask regularly: "Are you allowed to travel with me to Kansas City in order to accompany your exam from reader to reader explaining what you meant?  No?  So don't get in that habit now.")

(4) Ask for help on borderline calls.  The class is instructed to raise their hands and read me any answers they're not sure about.  Not generalities like "What if the student kinda hinted at the answer?"  I ask the student to read, verbatim, what is on the page.  I then make a call one way or the other, and we move on - just like an umpire.  

And if the student who wrote the answer tries to chime in what he meant, I politely say, "Since the answer needed clarification, it must be incomplete.  Please mark it wrong."

(5) Be transparent.  Just as a league doesn't assign the same umpire to the same team too many times, be sure you're mixing up occasionally who gets whose paper.  Have the graders write "graded by" and their name at the top of the page, and make it clear that accurate grading is a skill that you are assessing.  Ask students to place their own pencils and pens on the floor while grading goes on, so that the only writing utensil available is the red pen - that way, it's not possible to change an answer dishonestly.  

If you suspect someone is grading inappropriately to benefit (or hurt) a classmate, don't ignore it, but don't get preachy!  I've had small issues early on - students giving credit when they shouldn't, hoping to curry favor with a classmate.  Those were easily and definitively solved when I asked publicly but earnestly, "Luke, can you please show me why you marked this answer correct?  I think it's clearly wrong, but am I missing something?"  That's all it takes.

(6) Make instant replay available.  We have a standing rule - students may never, ever, argue or discuss with the person who graded their paper.  But they may circle in red a question they think was graded inappropriately, signaling me to take a look.  They can't talk to me, they can't tell me what they meant, they can just circle the question.  And, if the grading was indeed incorrect, I will change the score and let both student and grader know what happened and why.

Early on, usually I get a bunch of students circling their answers, hoping to argue for a better score.  That ends quickly when they can't talk to me to lawyer up.  If someone can't stop arguing and circling obviously wrong answers, I tell that student that I'll take off an additional point for each answer they challenge incorrectly.  (Kind of like how in the NFL a coach loses a time out if he incorrectly challenges a ref's call.)

Thing is, students are more careful graders than I am.  The process is quite fair - even moreso than if I combed through all the quizzes.

The most important point to keep in mind, though, is that the grading process is not even about fairness.  The goals are twofold - to provide an arena in which students are paying attention to physics facts, but also to establish that physics has right or wrong answers.  

Within a week my class has stopped arguing with me about grades.  They know what my answer will be - it is the student's responsibility to communicate correct physics the first time, in writing.  They've seen that the entire class is held to the same standard, that no one can sycophantically beg for points after the fact.  

26 October 2017

Vertical motion simulator for changing g

Screenshot from vertical motion simulator
at computercow.net
One of my favorite early-season assignments asks how much higher or lower a ball will fly when g doubles.  Most students recognize, or guess, that doubling g leads to a halved maximum height.  To their chagrin, they also discover that doubling both the launch speed and the gravitational field does NOT lead to "canceled out" effects and the same maximum height.*

* ...because height goes as launch speed squared.

Even in the first weeks of class, my students expect experimental verification of mathematical predictions, especially counter-intuitive predictions.  But, I can't easily take my PASCO projectile launcher to a planet with gravitational field 2g.

And here, then, is a perfect place to insert an animated simulation.  I stay away from simulations because they're emphatically NOT real.  Physics is in the business of predicting how the natural world works, not how programmers make it seem to work.  Nevertheless, appropriate programmed simulations can be useful for giving students a feel for experiments that can't be quickly or easily set up in lab.  

Problem is: I've never found a free-fall simulation that allows me to change both g and the initial vertical speed with which an object is launched.  There are some wonderful dropped-ball simulators, and others that do a good job with projectiles.  But nothing purely vertical with a varying g and v0.  If you know of a free simulation that does what I want, please let me know in the comments.

(Barry Panas, the Official Humorist of the AP Physics Reading and master Manitoban physics teacher, is right now screaming at me the same way I scream at baseball commentators: The Interactive Physics platform will do exactly what I describe!  When I had IP installed on my old computers, I used to use it.  Barry taught me everything I know about using IP.  But, I don't have that program anymore.  I need something free and quick. Sorry, Barry.)

Good news - I have a student this year who's a programmer.  I explained what I was looking for; in a day, he had something basic but useful.  Take a look at this link. I don't exactly understand how the "pixel" button works, but it allows me to zoom in or out.

And so, after we did this problem, I projected this simulation in front of the class.  We doubled both g and v0, and wouldn't you know, the maximum height didn't remain the same.  Physics works.

Disclosure - the link is to my son Milo's site; he is the student who programmed the simulation.

08 October 2017

Should universities award credit for AP Physics 1? Yes, a thousand times yes.

Gary writes with a big-picture question about teaching college physics at the high school level:

A college physics course would be either 4 or more likely 5 credits.  A history or language course is often  a 3 credit college class.  Why do so many high schools  treat AP Physics the same as the other AP courses?  It is difficult to explain to students, parents, school boards etc that the AP Physics will require much more time and effort than students are used to... I know that many universities are concerned about giving AP Credit especially to science majors.

Firstly, a university "concerned" about giving credit at some level for AP Physics 1 either hasn't done their research, or is operating from a set of assumptions about what "credit" means which is as out of touch with the reality of my students' experience as the Republican party is out of touch with contemporary musical theater.

The answer to Gary's first question is sort of sad, and often damning to the credibility of high school science courses.  Teaching rigorous high school physics is incredibly challenging, because we have to know our content backwards and forwards, we have to develop unique pedagogy... but we also have to navigate the most difficult political environment this side of congress.  As far as I can tell from extensive anecdotal evidence and personal experience: 

1. Most high school administrations have no clue about the comparative difficulty of the AP courses.  They understand *that* lab exists, but they don't have a real clue why or how laboratory work should be done.  They see their students write baloney with big words in English class, and earn passing scores; but then the same technique earns a 1 on the AP physics exam because physics can't be finessed.

2. Sometimes when the administration does recognize that physics is a different animal, it's not politically possible to treat physics differently.  Let's say they give AP physics more class time, or more academic credit, or a smaller student-teacher ratio, or they give an AP physics teacher an extra planning period to set up laboratory work... there WILL be complaints about "fairness" from other AP teachers.  Not just administrators, but lots of other teachers think that school should be about reading a book, remembering what's in it, then BSing the way through a discussion and a paper.  Why should physics be any different?  After all, they hated physics.

But what I don't understand is why any of that should impact universities awarding credit for good scores on the AP Physics 1 exam.  

The AP Physics 1 (and AP Physics 2) exam is outstanding and challenging - much more challenging than a typical college physics exam.  A student who earns a 5 has not only shown extraordinary mastery of the requisite concepts and skills, but also the aptitude to handle any further physics topic you can throw at her or him.  A student who earns a 3 has not just thrown dung at the exam hoping some would stick; such a student has shown considerable though incomplete mastery of the topic.

As a rule, scores from the old AP Physics B exam have shifted down one number.  Students who get 4s on AP physics 1 would have gotten 5s on AP Physics B.  Most importantly, those who used to pass (i.e. earn at least a 3) on the old physics B exam do NOT pass the physics 1 exam.   Why?  Because a mathematically talented student without physics knowledge could, on a physics B exam,* plug random numbers into random equations and earn enough credit to pass.  Not so in AP physics 1.  There are no "pity points" of any sort.  If you pass, you understand.  

* and in most college courses - that's the university level's dirty secret

In my mind, universities should be actively seeking out students with passing AP Physics 1 scores in order to give them credit and woo them to their school.  They are well prepared: perhaps for a physics major eventually, definitely for any rigorous quantitative work at the university level.  And the ones with 4s and 5s - department chairs should be recruiting them as they would a quarterback with NFL potential.


07 September 2017

How should a physics teacher use a "learning management system"?

A reader indicated that he's being pushed by his administration toward using the learning management system Canvas, especially for paperless testing.  Where do I stand, he asked?

My school adopted Canvas about four years ago.  While I'm not personally a fan, I recognize and acknowledge the major benefit to the student, especially the student at a day school.  All assigned work is clearly indicated on and accessible from a simple-to-use calendar.   Student misses a day of class - no worries, assignments are on Canvas.  Student is disorganized and loses assignment sheet, or forgets where to look online for my assignment - no worries, all on the Canvas calendar.  

My concern is partly that we are doing a large amount of organization for the student, rather than the student internalizing the organization skills for him- or herself; my concern is partly that significant technical hurdles to uploading and downloading assignments too often get in the way of teaching.  Nevertheless, in these matters I yield my own judgment to the consensus of our faculty.  Canvas has in general been a positive development for us.

I do not yield my judgment about physics teaching.  Physics teaching is different from teaching other subjects, and way too many people don't recognize that.  

It sounds like this reader's administration isn't considering how physics is done.  Yes, in some classes at my school, essentially all assignments and tests are handed out and submitted through Canvas.  That works fine for multiple choice, for pure text in an English or history paper, for straight-up numerical responses.  

As you indicated, though, physics demands communication in writing.  A well-presented problem consists of words, diagrams, equations, and numbers.  Annotated calculations or derivations often include circles and arrows and, well, handwriting techniques that I can't well describe or draw in a blog post.  I'd need hard copy.  

And so, when I create assignments in Canvas, I simply attach a file consisting of the problem set questions.  The actual assignment submission is always on unlined paper.  Canvas is still an important and useful tool, though, ensuring that everyone has the assignments available electronically in calendar format.

It is NOT POSSIBLE to appropriately test physics students using Canvas, or using any computer input.  Physics assignments require paper.  They require pen or pencil, and sometimes ruler and protractor, graphs, the ability to create or annotate diagrams, to draw and refer to pictures... 

If administrative fiat demands that you use Canvas for the multiple choice portion of your tests, so be it... I mean, multiple choice is multiple choice.  But for the free response homework and tests, I encourage the entire physics teaching community to continue to require hard copy.*  To do otherwise, I think, is professional malpractice for a physics teacher.

* Okay, okay, if you have a seamlessly working tablet with a stylus for everyone, perhaps that could work, 'cause that's the same input method as paper.

When the administration similarly requires computer tests and projects in your Studio Art class, then perhaps I'd reconsider.  Perhaps.  :-)