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22 November 2015

Exams... Huh! What are they good for?

Absolutely Nothing.

NO NO NO!  The trimester/semester exam is the most important teaching tool in my kit.  One of the great advantages to my school's physics program over the years has been our trimester calendar, in which we have a set of major exams before Thanksgiving, and another in early March.  We're about to lose that advantage, as it's pretty clear that our upcoming redesigned schedule will put us on semesters.  I'm okay with that, because the new schedule is likely to have so, so many important improvements: longer class periods, more down time during the day and during the week, more creative use of time outside the standard class day... if the price of all these benefits is one rather than two mid-year exams, so be it.

Yet, I become ever more frustrated with those who see the elimination of an exam week as a one-week gain in "teaching time."  No, folks, exam time is teaching time.  An exam period is the one portion of the school year in which I’m guaranteed to be able to expect diligent and focused attention from my entire class.  I use the exam – not just the exam itself, but the process of preparing for and debriefing from the exam, too – as my most important teaching tool. 

Would the soccer team countenance skipping the state playoffs in order to spend the season's last week on skill development?  I mean, the only reason we even have playoffs is because our egomaniac coaches are trying to imitate professional leagues.  Would the fine arts department cancel performances of the winter musical?  Production week is extremely stressful and time consuming; without the deadline and pressure of the performance, we'd have more time to rehearse and develop our roles.

Right?  Or nonsense?  Yet these are exactly the arguments I hear against exams in general: they're too stressful, they take away time to teach skills, we only even give exams because colleges do.   I would love to change the conversation about exams, not just at my school, but the world over.

Consider the following student phenotypes, and how they've benefited from both November and March exams over the years:

* The overwhelmed freshmen who were always behind were graced with hours upon hours of relaxed time to sit and study one subject for a while without six teachers screaming for assignments.  These folks built significant confidence with strong exam showings because they had the chance to actually prepare stress-free for a day.

* The borderline honors-regular students who didn't think they could handle the higher level class.  Strong performance on the exam often clinched the point:  YOU BELONG HERE.

* Contrariwise, the students who worked hard in honors but might not have belonged, got a fair evaluation of where they stood.  We could then make the decision for them to stay or to go based on an exam for which they had every chance to prepare – no fooling themselves that “oh, I’ll be able to study better for the AP exam in the spring.” I note that my physics teaching peers have been quite jealous of my Thanksgiving exam period, in which I can drop a junior or senior into regular physics without that showing up anywhere on his transcript.  The fact that I can reasonably say “stick it out through the trimester exam” allows me to reclass students if necessary when we’re only through 1/3 of the year and they’ll still be successful in the lower course.

* The smart freshmen who don’t see the connection between careful, diligent everyday work and true understanding.  These students’ poor exams allow me to say in so many words, “See, here’s why you have to pay attention every day; you can’t just expect to ace the exam, like you did in middle school.”  These folks generally turn in much better work in the weeks after Thanksgiving.

* The students who argue with their teachers about whether they’re doing enough or the right kind of studying outside of class.  The Thanksgiving exam allows us to say, “Hey, we just tested your contentions – you had all the time in the world to prepare, and you didn’t do well.  Now maybe you ought to listen to your teacher’s suggestions.”  (Or, "Yup, you're right, you aced the exam, maybe we should back off and let you study your way.")

* The students who utterly bomb their first set of freshmen exams… but yet have ten more exam periods on which to learn from their mistakes and improve.

* Every Senior I Have Ever Taught who, without a March exam that colleges might see, would have stopped working seriously months before.

An exam is not an evil, onerous implement used by teachers to torture their students.  An exam period is a pedagogical tool, a way of showing students unambiguously how they’re doing, a way of showing teachers what the students have really learned.  The process of preparing for a trimester exam is one of learning, of reminding everyone how the course fits together.  Students take my review sheet and its corrections very seriously, because of the upcoming exam; I hope no one believes that a cumulative review would be as effective without an imminent formal “exam.” 

Furthermore, even after the exam is given, the exam is still useful – I invariably use the exam throughout the following trimester as a way to remind the class of previous topics.  “Tomorrow we will take a quiz on which you will explain the answers to exam problems 35, 44, and 16.”  Not only do students go back over their exam , but they take the exercise ever more seriously because they know that another exam will be on the way.

So the next time a student, parent, or college asks incredulously, "why do you make your students suffer through cumulative exams?" please respond with some of the above arguments.  Let's try to stop the fear mongering. We don't tell a football player "You'd better not screw up this championship game;" we don't let players tell each other "Oh, I just know you're going to screw up and lose this championship game for us."  So let's not say the exam equivalent, "You'd better study extra hard so that you don't fail," or from a student, "I just know I'm going to fail these exams."  Let's help the wider world understand why we give exams, why we enjoy giving exams, why the entire process of an exam week is as critical to the learning process as is any week of lecture and homework.

And then let's let the quality of our exam preparation, the exam itself, and the debriefing process be worthy of the time we dedicate.  But that's a topic for a whole other set of posts.

07 November 2015

Mail Time: Should I teach the elastic collision equation with velocities?

A correspondent writes in, in reference to an AP Physics 1 class:
[Edited for space]:

I have been teaching elastic collisions problems using an elastic equation : Vf + Vi = Vf + Vi to solve problems that are missing two of the velocities. We discuss that as long KE and momentum are conserved then we can take KE and momentum equations and divide them to get the elastic collision equation with just velocities.  

I recently was tutoring a former student who is now in a local college about solving these types of problems and she told me that her professor said that the equation does not work and that its not physics! She was told that I was completely wrong!!! I immediately went to a Giancoli textbook. Giancoli does derive this equation following same reasoning that I derive for my students.

BUT... I hate to think that I have been teaching this wrong!  I was hoping you might be able to offer some clarity.    I went through [the professor's] problems and compared my solutions to the professor's solutions and I do get the answers he gets, just in a lot fewer steps.  Any suggestions? Should I not teach elastic collisions this way?

Fascinating question.  My answer is twofold -- one answer on philosophy, one answer on content:

1. You are teaching absolutely correctly.  I don't know what her professor is on about.  Remember, "professor" means neither "good teacher" nor "better than you at introductory physics."  It's so easy for a high school physics teacher to be intimidated by folks with PhDs, or by education "experts."  As long as you are carefully self-evaluating -- and you obviously are, based on paragraph 3 above -- then do things your way.  I can't emphasize enough that even my well-tested methods and ideas are not for everyone.  The best physics teachers, like the best chefs, are creators, not imitators.

2. On this specific issue of elastic collisions: You might consider why it's necessary to teach quantitative solutions to elastic collision problems at all.  Yes, you need to be able to check whether a collision is elastic by comparing KE before and after the collision.  But even with the simplified relative speed equation that you reference, solving for speed in elastic collisions is more calculation that we need for AP 1, or even for my taste in any intro course.  That's not to say you're wrong to teach it, as I did for years... I just don't think it does enough to be worth the time it takes to teach and solve the problems.

21 October 2015

"I didn't know how to do the problem, so I left it blank."

Puppy Dog Eyes from
Yeah, in the first weeks of school I hear that a lot from 9th graders.  I get a real cross-section of 14-15 year old boys, the quality of whose middle school educations are all over the map.  These folks are generally good boys who care about doing well in school.

And that perception of "good" is actually an obstacle to teaching physics.  I recognize that universal, quality education is an American core value, one that I obviously share with most of the country.  I acknowledge that elementary and middle school teaching requires different skills and techniques than I regularly employ -- reading fluently, following directions, writing legibly, sitting still when required are all skills that I take for granted in my 9th graders, while they must be taught to 5th graders.  I mean, I know that most of my class will be less-than-accomplished at these basic skills; but I am confident that they have been previously taught and internalized.  It's my job to help the students execute these skills in the context of learning interesting and rigorous physics.

To me, a "good" student coming out of middle school is one who understands the basic procedures of how to learn.  That's not how my 9th grade boys seem to see the world, though.  To them, a "good" student gets the right answers.  Being wrong equates with moral failure.  Thus, they seek the right answer through any means necessary, including hangdog eyes and a submissive "but I just didn't know what to do, please help me."

The problem that I face is that too many of my students are used to the teacher feeding them answers in exchange for that puppy-dog-look.  I'm sure teachers don't think of what they're doing as feeding answers, but they are -- responding to a "clarifying" question, suggesting something to think about, or giving away the first step in an already-taught-process might allow the student to overcome a mental block.  But what's that student going to do on a test?  Well, the dirty little secret in so, so many high school classes is that the teacher does the same prompting during tests.  No wonder students have trouble with SAT and AP exams in which no help is available.

Now, before you go ballistic in the comment section about how cruel this Jacobs guy is, understand the context.  I will never, ever engage with a student who presents me with a blank paper and asks for help.  However, I will always and enthusiastically engage with a student who presents me with a serious written attempt at a solution.  

I explain this difference again and again to my classes.  Nevertheless, for weeks I face frustrated students who ask, "Well, can't you just tell me what wavelength means?  Can't you suggest which equation to use?  This problem makes no sense, can you explain what I'm supposed to do?  AArrgh!"  I respect the frustration.  They don't want to be wrong, 'cause that's the same as being bad.  And I'm not helping them be right, so I'm forcing them to be bad.  What a cruel, cruel man.

Since most of my students are athletes,* I often respond with a sports comparison.  "You're the goalkeeper for a penalty kick.  You don't know which way the opponent will shoot.  So... you stand there with your head down, and don't move because you're afraid to be wrong?!?"  (No sir, I pick a direction and dive.)

*for a given value of "athlete", anyway

Or, "You're the quarterback, and the defense lines up differently than  you expected.  So, you take the snap and stand there sadly, until you're sacked?!?" (No sir, I run somewhere, or make the best play I can.)

Or for the non-athlete: "You're in a play, and the other character in your scene drops an important prop.  So, you stop the show, hang your head, and walk off stage 'cause you don't know what to do?!?  (No, sir, I cover as best I can and continue with the scene.)

A blank problem is a sin.  A wrong answer is an opportunity to learn.  I have to hammer these facts of life over and over, for several weeks.  That means blank problems suffer enormous grade penalties, yes, but also they earn trips to special afternoon study hall, required extra help sessions, notes to advisors, and even notes to parents where necessary.  On the other hand, students learn quickly that the worst consequence of a wrong answer is the loss of a point.*  Thus, it's far more effort to leave things blank than it is to make a reasonable guess.

* They also learn quickly that the loss of a point is not relevant in the grand scheme of the universe.

You probably see how things go next: the students often discover that their answers are righter than they thought.  When the answers aren't right, they have context for my explanations -- not "oh, Mr. Jacobs said the wavelength is 2 m" but "oh, I almost had it, I just didn't realize that the wavelength had to be determined from the diagram."  The latter reaction is far more likely to result in correct answers in the future.

It's not about today's homework or test -- it's about long term understanding and performance.  That's the point that so many teachers miss.  We all want our students to do well, we all want positive feedback from students and parents.  But I want that feedback at year's end, when they experience for themselves just how confident and well prepared they are for their physics exam compared to all other exams.  I want that feedback from alumni, who universally describe not only how much fun my course was, but how well it prepared them for other academic endeavors.  

Right now, though?  I want them to write their best attempt at answering today's question.  And if they're wrong, well, they'll find that dungeons do NOT await, contrary to their conditioning.

05 October 2015

How I'm starting my 9th grade AP course -- position-time graphs

Juniors and seniors like to sit still and take notes while I talk from the front of the room.  Sure, they want to be entertained and impressed by quantitative demonstrations, but nevertheless they don't initially appreciate active, open-ended classes.  It takes considerable work over the course of the year to convince upperclassmen to relax enough to deal with true "inquiry."

Freshmen, on the other hand... they are thrilled NOT to have to sit still.  They're willing to try things that they might get wrong.  And they're not going to remember much that you say to them from the front of the room, anyway, so you might as well give them an open-ended class.

In order to act on these observations, I now begin my AP classes for seniors differently than I begin my AP classes for freshmen.

For seniors, I begin with equilibrium.  I do demonstrations with friction, normal force, objects hanging from strings at angles... for each, I show how to predict amounts of force using free body diagrams, then we verify the predictions with scales.  These are strong classes, allowing my students to quickly figure out how to solve complicated physics problems, setting the stage well for the year's material.

But for 9th grade, I'm starting with position-time graphs.  I'm doing the very same exercise I do with my regular conceptual physics course, but over one or two days rather than four or five days.  

I briefly demonstrate the use of the motion detector with the Vernier labquest.  I hand out just the facts on this sheet about position-time graphs.  (I'll hand out the other facts later.)  I give each student a copy of this worksheet, as shown at the top of this post:  It has a position-time graph, along with three questions about the physical manifestation of the graph.  Each student gets a different graph, which I draw in by hand.  Some represent constant speed motion, some represent speeding up or slowing down.

Each student answers the questions on the worksheet one at a time, bringing the answer to me after finishing each one.  I either say "good, move on to the next question," or I explain the mistake in reasoning and ask the student to try again.  

Once all three questions have been answered correctly, I send the student to the back of the room to do the experiment.  Ideally, in a few minutes he comes back to show me a labquest with a correct position-time graph displayed.  See: prediction and experiment, all together in one exercise.  

After each student has done two or three of these, I give out a similar worksheet and facts about velocity-time facts.  And so I can teach motion graphs in just a couple of days.

I tried this activity with seniors.  They didn't like it... they were angry with me when I said "no, sorry, that's not right."  Even when I sent them to the back to do the experiment, even when they came back with results that didn't match the graph, they sulked, as if it were my fault that the carts and sensors didn't adjust to their lawyerly interpretation of the laws of physics.   No, open-ended, independent class work with seniors was a bad idea at the start of the year.  It caused the students to hate me as a proxy for hating the world.

But the wide-eyed freshmen on their first day of an intimidating AP physics course?  They were thrilled to be doing something hard but manageable.  They loved seeing whether their predictions were right or wrong.  They loved the confidence built by revising their ideas until the experiment matched their prediction.  

People wonder why I want to teach AP Physics to freshmen... and this is why, in a nutshell.  My freshmen are wide-eyed puppies, still thrilled by discovery.  Despite the difficulties of structuring an AP course for younger and less-experienced students, the enthusiastic cooperation from my ninth graders compared to the sullen grade-gaming of too many of my seniors makes any amount of extra work worthwhile.

27 September 2015

How a visitor improved my class's confidence

I teach 9th grade at a boarding school for boys.  When we host prospective students on campus, they often come to my class.  I don't generally let them sit passively and watch -- I make every attempt to get them involved in the day's activity.

Yesterday (yes, we teach on Saturdays, aren't you jealous) a prospective student sat in as I introduced mirror ray diagrams.  We had already covered ray diagrams for converging and diverging lenses, so the class already had the general principles of the topic ingrained.  So class consisted of just a few elements:

1. A three-minute quiz based on questions on our recent assessment.
2. Grading that quiz
3. Six minutes of me demonstrating two mirror ray diagrams predicting the location of an image
4. Setting up a converging mirror to verify the ray diagram's prediction  
5. Handing out this worksheet which includes nine situations for students to practice ray diagrams

At step 5, I put on music and allowed students to work at their own pace.  They brought up each completed diagram for my approval.

So what did the visiting student do?  He didn't know about ray diagrams, right?

No, he did not.  I gave him a copy of the quiz just so he could follow along.  I gave him a copy of the worksheet.  I asked him to make his best effort to join in, attempting the ray diagrams and showing me his work.  To this gentleman's credit, he did -- in a class of students a year older than he, when he must have felt very much the outsider, he joined in.

And, of course, he got things wrong.  In his first attempt, he didn't use a straight-edge.  Many of my class made that mistake seven days ago, when we first tried lens ray diagrams.  I gently explained that he needed to use the ruler I had placed on his desk.  So he went back to try again.

The next time he came up to see me, he had drawn a ray incorrectly, and his image was in the wrong place.  Thing is, my students had made exactly these kinds of errors a week ago, too!  It was cathartic for my guys to help this prospect out.  Everyone in my class was friendly, helpful, welcoming... 

...and a wee bit smug, knowing that they were beyond the rookie mistakes.   

At the end of class, I shook hands with the prospect.  He seemed relieved to be done, but also quite a bit proud to have joined this physics class seamlessly.  

And a couple of my guys walking out with the prospect also walked a bit straighter.  As a student, it's easy to lose sight of the significant progress you've made, even just a few weeks into the school year.  When new material comes at you nearly every day, when tests and quizzes are raining down from every subject, it's so easy to focus on "failures" -- you missed this question, you didn't demonstrate this skill, you didn't remember this fact.  Our visitor gave my students the opportunity to see for themselves the things they DID know, the skills they HAD developed.  Helping this youngling out made them feel good, reinforced their own knowledge through teaching, and built tremendous confidence.

And the youngling?  He kept working, kept listening to my students' advice with a smile, neither ran away screaming nor folded up silently in an intimidating academic situation.  So I very much hope to see this guy in my class next year.

14 September 2015

"Motivation" for completing in-class exercises... inspired by the AP Physics reading

I've heard the AP Physics reading referred to as a "sweatshop."  The moniker is full of hyperbole, of course, yet unironic.  At the reading, teachers used to independence and flexibility find themselves required to work unyieldingly to the clock.  At 8:00, you sit and grade for two hours.  Take a break -- exactly fifteen minutes, exactly from 10:00-10:15 -- and keep grading until lunch.  One prescribed hour for lunch, and back at it... well, you get the idea.

When you've been grading for days, and your brain is tired, and it's still another hour before lunch, what's to stop a reader from just sitting there and pretending to work?  Or from taking a 55-minute bathroom break?  This what I mean by the hyperbole of the sweatshop analogy.  The supervisors at the AP reading have no real power.  No whips.  It's even vanishingly rare for someone to be sacked on the spot (and the presumptive sackee still has a cushy tenured professorship to return to, so even sacking is an empty threat).

The only leverage that the reading leadership truly holds over the grunts is professional pride... and that's powerful leverage indeed.  Teachers generally want to do things right.  They care.  They don't want to look like the weak link in front of colleagues.

So, each day, the table leaders list each reader in the room on a wall chart.  As a reader finishes a pack of 25 exams, he or she makes a tally mark in the correct space on the chart.  There, laid bare for the entire room to see, is a permanent record of how much each person has contributed to the group effort.

Now, the leaders emphasize over and over again: the reading is not a race.  Accuracy is far more important than speed.  There's no prize for the person who reads the most exams.  Just do your best, and speed will come.  No pressure.

Nevertheless, consider a session on day four of the reading in which most of the room reads ten packs of exams or so, but Jason only reads three packs.  How does Jason feel?  How do his colleagues in the room feel?  No one, especially the table leader, will likely come to Jason and have a word about his slow relative reading pace.  The worst consequence for Jason will likely be some stares from his colleagues.  Nevertheless, Jason will have taken a serious blow to his professional pride.

If Jason still is slow in the next session, perhaps the table leader might offer some tips about speeding up -- always reminding Jason that speed is secondary to accuracy, and isn't truly that important.  Perhaps in the beer tent that night Jason might take some good-natured needling from his friends about his slow day.  But the real incentive here is that Jason will want desperately to feel like part of the team... no one at the reading wants to feel like he or she has let down the communal goal.

So what does this have to do with your class?

A standard type of class, especially with my 9th grade, involves students working at their own pace on in-class laboratory exercises.  I'm often asked, how do I motivate students to stay on task?  Certainly I offer credit for each completed exercise, but to a 14-year-old, it's likely that gossiping with friends or secretly checking a fantasy football team will trump physics work any day of the week.

Well, to start with, I have a pretty good classroom presence.  I generally notice quickly when conversations turn to sports, music, or sex rather than to physics.  Just a friendly but firm call-out from me, especially early in the year, can remind students that I'm paying attention, and that I expect them to focus.  My eyes and my words take care of egregious issues.

What about the student who would rather sit with his mouth hanging open rather than do the tough work of engaging mentally with physics problems?  I do require frequent trips to the front of the room to check with me.  When I haven't seen someone in a while, I may inquire why not.  

As at the AP reading, though, the real incentive is a transparent display of progress.  Students earn credit for each exercise they complete.  To keep track of how many exercises each person has done, I use an AP-style tally board -- see the picture above.  It becomes a bit uncomfortable if Jason hasn't finished an exercise at all, while his classmates are all on number five or six.

I've observed that 9th graders aren't usually embarrassed about poor or lazy performance when the teacher is the only one who knows or notices.  "Oh, sorry, physics is hard, I'll never get it, I'm just not that good."  But when their peers are the ones taking off points on a quiz; when their peers observe perverse slackage; when their peers say "you know, we've only done a problem like this four times, it's not that tough" -- then those 9th graders tend to pick up the mental effort.  

Please understand, the intent of the progress board is not to shame anyone.  Taking a cue from my years as an AP table leader, I emphasize repeatedly -- physics exercises aren't a race.  No one gets a prize for being fastest.  It's more important to be right than to be sloppy and quick.  I never call anyone out merely for a failure to keep up.  Nevertheless, the board is there, staring at the class, giving some folks second thoughts about taking a bathroom break, perhaps encouraging someone to get just one more done before the bell rings... 

31 August 2015

Electric fields and potentials demo in corn oil... and why the voltmeter didn't work.

Several years ago I shared Wayne Mullins' demonstration of electric fields and potentials.  He used two metal PASCO masses placed parallel to one another in water to produce a uniform electric field in the water.  The electrodes were connected to ~25 VAC.  The linear variation of potential with position between the plates can be demonstrated with a voltmeter; a couple of fingers spread in the water (done carefully -- read the post!) can show viscerally what a potential difference really means.

Today in my visit to TASIS American School in London, blog reader Scott Dudley showed me and his classes a similar demonstration.  He connected 2000 VDC to two small wires placed in a pool of corn oil.  A sprinkling of some grass seed between the wires showed these long particles lining up with the electric field lines, as you can see in the picture.  This demonstration provoked three thoughts from me.

(1) Why would the particles align with the electric field rather than along the equipotential lines?  Teacher Dallas Turner once suggested using goldfish in water between the electrodes to show the equipotentials.  The goldfish will align perpendicular to the electric field so that no current runs through their bodies due to a potential difference.  So what makes grass seeds different?  I expect that the seeds are slightly polarized... then they experience a torque because they're dipoles in a uniform electric field.  That torque aligns them with the field: the positive end is forces as close as possible to the negative plate, and vice-versa.  (Right?)

(2) I suggested that Scott use a voltmeter to map the equipotential lines, as I do in Wayne's demo.  So Scott gamely stuck the probe in the oil... and nothing.  No reading.  Why not?  Because, as Scott immediately pointed out to me, the meter produces a small (few milliamp) test current in order to measure a voltage.  The oil is a strong insulator, thus not allowing the meter to make the measurement.  The demonstration works fine when I do it in tap water, because tap water is quite conductive.  Of course, Greg... that's why I need water in the first place rather than just the air in between the two electrodes.  And that's why the "field mapping" lab exercise is generally done with conducting paper.

(3) The AP Physics 2 exam does not deal with traditional field lines.  Instead, field mapping is done using "vector fields" in which a multitude of arrows indicate the magnitude and direction of the electric (or magnetic or gravitational) field at various positions.  The grass seed can help develop an understanding of the vector field representation.  Each individual grass seed is pointing in the correct direction; now, draw each seed, but draw it bigger or smaller depending on the strength of the field at that position.  Nice.

Thank you to Scott for hosting me at his school.  I met a number of clearly excellent teachers; I wish I could have spent more time with everyone there.  Perhaps I can convince my school to send me to London a second time... :-)


22 August 2015

What the science teaching community can learn from NBC's soccer coverage

The best sporting events need no over-the-top, carnival barker-style salesmanship in order to draw a large audience; physics, or science in general, similarly needs no hype to make it interesting.  Bear with me as I give a brief tutorial of American sports coverage.  I'll get to the physics teaching connection at the end.

For decades, baseball was the only American sport that mattered.  Coverage included the dulcet voices of Vin Scully and Al Michaels, who took the game seriously, even though they didn't take themselves too seriously.  They knew that baseball, interwoven with a century of history, would sell itself -- their job was to tell the story of that days' game.

Baseball lost its title of "America's Pastime" to football not because of underpromotion, but because football is by far more suited to television and 21st century lifestyles.  When FOX took over national telecasts in the late 1990s, they tried to change baseball's downward trend in popularity with wrestling-style promotion: "NOW!!!  PUJOLS VS LESTER!!!!  LIVE!!!"  If anything, FOX has turned people off by misrepresenting their product.  Baseball is not suited to such treatment.

On the other hand, the championships at Wimbledon and the Masters golf tournament explicitly reject the typical "loud men screaming and laughing at each other" coverage that is typical for an American sporting event.  The tournament hosts insist upon a serious, nay reverent broadcast; yet they draw extraordinary television ratings, and tickets are next to impossible to come by.  Funny, that.

Then there's soccer.  For most of my life, what little soccer coverage I could see tried too hard to sell sizzle.  "Americans don't know about this game, and it's a boring game, to boot," said the producers (who also knew nothing about soccer).  So the announcers talked down to us: "Now, when I was little, my coach called this big box here the 'mixer.'  You're supposed to put the ball in the mixer to score goals."*  The pregame shows tried to explain the rules of the game again and again in excited voices, rather than to tell the story of the game's history.  The broadcast ignored everything but items deemed of direct relevance to Americans, who had no soccer history anyway.  It was all so, so condescending to even the mildly knowledgeable fan.  No wonder no one watched: those who were serious soccer fans felt talked down to, and those who weren't certainly didn't fall for the artificial sales job.

* Not kidding -- approximate quote from 1994 World Cup coverage.

Let's examine that paragraph in a science teaching context.  Rewrite, substituting science for sport.

Then there's science.  Too many science education programs try too hard to sell sizzle.  "Kids don't know about science, and science is boring, to boot" say the people providing education grants, who too often know little about science or science teaching.  So the teachers, program directors, and presenters talk down to students.  "And without science, we couldn't have iphones, and you couldn't twitter to your friends!  Isn't science great?"  Classes are taught facts and equations, without connecting those facts and equations to experiments that students can themselves perform.  Topics are ignored unless they can be made immediately "relevant to everyday life," even if said relevance is so forced as to be a camel through the eye of a needle.  It is all so, so condescending to even the moderately intelligent student.  No wonder people get turned off: smart, otherwise interested students feel talked down to, and those who aren't already interested don't fall for the artificial sales job.

Soccer coverage has changed.  In 2008, ESPN tried something different.  They put on Europe's premier soccer tournament, one that did not involve a single American.  They named Bob Ley, perhaps the only prominent American broadcaster with a bona fide soccer background, as the studio host.  They gave up trying to force the use of American-accented commentators, and instead hired the best, most experienced soccer commentators in the world -- even if that meant hiring foreigners.  They told the story of the tournament on its own terms, not attempting to adapt to an American audience or an ignorant audience.  Point was, if soccer was so great, this major tournament which drew hundreds of millions of watchers in Europe would sell itself.

And it did.  People watched, and talked about the games and the stories.  The drama was authentic, the audience was captivated.  

Now, NBC broadcasts the English Premier League in the US using the same principles.  They tell the story of the league from a true fan's perspective, trusting the audience to keep up.  Just like Apple doesn't have to oversell the iphone, just like google doesn't need to hype its search service, NBC recognizes that the Premier League is a product that needs no enhancement, as long as the commentary is smart and authentic.  NBC's ratings are through the roof, despite the lack of on-air shouty salesmanship.

Science sells itself, as long as the teacher is good.  There's a reason that so many of you reading this are interested in science -- and it's not because someone screamed at you that science is FUN!  While many of us do some crazy-arse things in our classrooms, it's not the craziness that wins our students' hearts and minds.  It's the subject we teach, it's the way we communicate our deep knowledge of the subject, and it's the way we relate to our students about our subject.  Problems come when teachers *don't* know their subject or can't build relationships with the class.  Feigned enthusiastic salesmanship doesn't make those problems go away.

So please, folks... let's encourage science teaching in which the teacher takes science seriously.  Let's encourage expert teachers, both experts in subject and experts in relating to students, to do their thing the way they see fit.  Let's encourage more folks who are experts in one of these skills to become expert in the other.  

But let's not oversell science as a discipline.  There's no need.  We have an amazing product that a lot of people want.  We just have to manage the queue and provide outstanding customer service.

02 August 2015

A lesson in percentages

I'm hardly the first writer to kvetch about how the dang kids these days -- or any day, really -- don't have any sort of number sense.  My kid is working on his summer math assignment, which includes a page of percentage problems.  The questions themselves are not just reasonable, but important.  "What is 31% of 75" or "28 is 25% of what number" are to mathematical literacy what the offside rule is to soccer -- not everyone understands, but you'd dang well better understand if you want to be considered fluent.

My complaint, therefore, is not that Milo's class is studying the wrong thing.  It's how they approach the problems.  He is required to do the problems the same way I was taught 30-odd years ago:  set up a proportion, translating English to mathematics.  In this parlance, "of" means to multiply, "is" is an equals sign, "percent" means to make a fraction over 100.  No calculator is allowed.  And thusly, Milo and his classmates usually get the right answer.  They often don't notice when they do a routine backwards and say that 31% of 75 is 220, but they usually get the right answer.

I've no doubt that there is some sort of validity to this pedagogy, especially if some sort of national exam is going to require precise answers to such questions with no calculator.  But consider: beyond the test, what do we really want functional high school students and adults to be able to do with percentages?  I personally would prefer my class to be skilled estimators.  What's 31% of 75?  It's about 25, or maybe 24, because 31% is just about a third.  And I would prefer that no one in my class or family* rejoin "well, actually, one-third is 33.3333 repeating percent, so you're wrong."

* For their own sake, so they don't get thrown in the scorpion pit

Me, I'd teach this topic like a video game.  

Start with obvious reference percentages: 50% is a half, 25% is a fourth, 33% is a third.  And use them intuitively to solve problems quickly.  For example, I'd set up a competition: everyone gets 30 seconds to do, say, five no-calculator problems with just these obvious percentages.  Score something like one point for getting "close" in a way defined by the teacher, and an additional point for being right-on.  Guessing is encouraged, and essentially required by the time limit.  Students are practicing making intelligent guesses, and refining their guesses.

Once the class is getting bored with the obviousness, do tricksier problems.  Now the additional point would be awarded to the student closest to the right answer.  Don't demand any formal work or method, but discuss and share methods.  After doing, say, "What is 66% of 210," one student might suggest they knew that the answer had to be more than 105, because 66% is more than half.  But perhaps someone else noticed that 66% is twice 33%, and so is two-thirds -- and perhaps someone else explains how they estimated 2/3 of 210 without painstakingly dividing by three and multiplying by two.  

What does this have to do with physics?  I use essentially this same method when teaching circuits to freshmen in conceptual physics.  They learn to estimate, not calculate, voltages across series resistors and currents through parallel resistors.  And, by unit's end, they have a better sense for the answers than do seniors who have been taught to calculate.

I understand math teachers' obsession with routine and algorithm.  When weak students -- students without any innate number sense, and without any serious interest in the subject -- simply need to get exact answers, well, algorithm can be a friend.  I'm telling you, though, an estimating approach can work wonders.  Even weak students can make progress by guessing and checking.  I've seen it happen.  If that culminating test is multiple choice, even the weak students will be able to pick out correct answers from a lineup.  

And, perhaps if a page of problems didn't represent a multi-hour sentence to proportions, cross-multiplication, and hand arithmetic, such students might develop an interest in the subject.  Or at least a competence with it.  

29 July 2015

Why do I teach: a rather prickly response

My school posed the entirely reasonable, in context, question: Why do you teach?  Each faculty member was asked to respond in a narrative and post to our faculty development site.

The folks who asked the question are friends; they're not just colleagues, they're the best teachers at the school.  As you see below, I take offense at the question, but not offense toward the people asking it.  They didn't know, were unlikely to know, why they pushed my buttons.  

Me, I still don't understand why teachers are expected to have kumbaya moments around the fireplace in regard to their employment, yet e.g. bankers, videogame programmers, and professional athletes are not.  Nevertheless... and with advance recognition that I very much enjoy my job and my school...

Why do I teach?

This answer is going to be quite a bit prickly.  I know this exercise was intended in good faith and without ulterior motives.  Yet, the question itself hits a major nerve.  

Short answer: None of your business. The question is offensive to me, though I know you intended no offense.

Most folks in academia are aware that seemingly every woman physicist has a story about someone in her life – family, professors, colleagues – who made an extraordinarily rude statement suggesting that she is in the wrong profession for a girl.  “You’ll never get a husband as a physics major,” or “Why don’t you take this lower-level class, the girls usually need a bit of catch-up,” or, famously and recently, “Three things happen when [girls] are in the lab: you fall in love with them, they fall in love with you, and when you criticize them they cry."

What folks don’t often recognize is a different social problem faced by physics teachers, especially male physics teachers.  Many of us have stories of family, administrators, and colleagues who don’t quite understand what a person with a degree in a “real” or “useful” field – and a man, to boot – is doing as a teacher. 

In interviews I was asked the question, “They say those who can, do, but those who can’t, teach.  So what made you decide to teach?”  The automatic assumption was that a person with physics and engineering degrees must be a crappy engineer indeed if he must resort to teaching for a living.  I’ve been asked repeatedly over the years, “why don’t you use your physics degree?” as if I’m making waste of said degree by teaching.  And, of course, “Gregory Charles, we paid all that money to send you away to an elite college, and you’ve decided to teach?  What are you thinking?!?”  Somehow, my sister with a theater degree from Dartmouth never got those sorts of questions when she began her teaching career.

And these questions are from well-meaning people.  I’m not even including the outright condescending discrimination from female colleagues and administrators who have no use for men in education.  I mean, obviously, a man who teaches is either gay, perverted, or on a power trip to become an administrator, right?

Then there’s the Soviet undertones of the question.  “Let’s all share why we’re so happy living in a Workers’ Paradise.”  What, this person isn’t happy?  He wants more of a say in how paradise is run?  He mentioned that perhaps the education establishment subjects us to vacuous dogma rather than encouraging engagement in substantive, intellectual discussion with creative, professional craftspeople?  He’s obviously a troublemaker sowing dissent and discord.  Take him to Lefortovo. 

I guess I’d like to rephrase the question… of course smart, interesting people choose to teach.  That’s obvious.  The question should instead be directed to the less intelligent or less dedicated folks, and should say “How in the hell are you a teacher?”

Why do I teach?  Because it pays the bills, I’m good at it, and I usually enjoy my students and my colleagues.  That’s all you need to know.  That’s all I’m willing to state publicly.  Actions speak louder than words: I encourage you to judge my commitment to my profession not by this sort of essay, but rather by the feedback from two decades of students, from colleagues at our school, and from fellow physics teachers around the country.