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26 December 2014

Teaching seniors after Christmas: hints and ideas

Our faculty is currently involved in a brainstorming exercise in which, without practical constraints, we suggest how the school could or should change programmatically to better address our students' needs.  Certainly I'm hearing some excellent ideas (though some of them are only excellent in the absence of friction and air resistance, so to speak).

A large number of these ideas suggest sweeping changes to the structure of the senior year.  I've many times heard our faculty -- and other faculties -- hold forth on the moral deficiencies of late-season seniors.  Amongst all the kvetching and suggestions for change, I wonder... are we trying to solve a problem that doesn't exist?  Or, at least, are we trying to solve a problem that could better be prevented than solved?

A number of teachers have quite positive in-class experiences with late-season seniors, without internships, final projects, field trips, or any other major gimmickry.*  If a class is truly important and useful, it should sustain students' interest regardless of whether those students need a good grade to ensure college admission.  To a very large extent it's the teacher's job to structure the class so as to keep students -- seniors included -- invested.

* MINOR gimmickry is abundant among the best senior teachers.

So how do successful teachers of seniors sustain interest, even though all seniors (to one extent or the other) have one foot out the door in the spring?  Here are some tips.  Some are from my own experience; many are from observation of and discussions with the best teachers of seniors that I know.  Please submit your thoughts in the comments.

* Deal with seniors are they are, not as we wish they were.  Seniors always prioritize things other than your class; as the spring advances, my class drops down the list.  I may not agree with their priorities, but it would be silly not to acknowledge them.  I set in my mind from the beginning that I am not going to take personal offense at seniors' attitudes, nor am I ever going to lecture them about their senior slide.  I vow to treat students with respect, even when their decisions don't command respect.

Front-load your course.  We know the senior slide is going to happen; conversely, we know that seniors are heavily invested early in the year, when their grades "matter."  So push, push, push the pace.  I cover at least half of my material in the first trimester.

Don't let one or two obnoxious seniors poison your mindset.  Even the best teachers of seniors don't have a 100% success rate.  When a student is being irrationally obstinate, do your best to patiently ignore him.  Don't let him rile you up.  If he's bringing the whole class down, dispassionately remove him from the situation (i.e. boot his arse out of class without drama); but whatever you do, don't engage or argue.  It's not going to help.  Think about how the rest of the class feels -- they're probably embarrassed about their obnoxious peer, but he's still a peer.  They don't want him disrupting class, but neither do they want the teacher to become angry or aggressive.  Be the welcome bringer of peace, not the fearsome champion of war.

* Develop positive relationships with the class early on.  While you are not expected to be best buddies with your students, they need to know that you care about them.  Expect the highest level of effort and performance, yes.  But in everything you do, from your words to your body language to your actions, show your students that you're doing it for them.  When someone screws up BEFORE the senior slide, treat him firmly, fairly, and compassionately.  Know that everyone is watching you, all the time.  If you react hostilely to one student, even if he deserves your hostile reaction, the rest of your class feels like you've reacted hostilely to them, too.  Don't underestimate the teenager's desire for vengeance against those who, in their view, take their authority too seriously.  

Conversely, don't underestimate teenagers' positive ethical underpinning.  If you are seen to be fair, patient, and on their side, the silent majority of your class will support you.  When that one bastard starts being a jerk to you in March, you want someone to take him aside and tell him "not cool, man, back off."  That does, in fact, happen... if you do the front-end work to earn such quiet support.

* Make even more effort to do something different every few days.  There's no cure-all for times when students would rather be cavorting in beautiful spring weather than sitting in your class.  Certainly the physics teaching literature, this blog, and shop talk will yield numerous suggestions of productive but different styles of class: whiteboarding, socrative, the physics walk, lab challenges, test corrections, and more are excellent ways to add variety.  Whatever the specific activities, it's that variety that's critical for seniors.  Freshman need routine; spring seniors need to break out of their routine.  

* Taper.  You might reasonably expect 45 minutes of work per night early in the year; by April, that expectation should be down to about 15 minutes.  It's a bad idea to stop giving homework altogether, or even to reduce the frequency with which assignments are due; however, each assignment can become smaller in scope.  Swimming and track coaches are familiar with this idea of "tapering" toward a championship meet.  The physics brain muscles are already strong from the hard work students have done early in the year.  In the spring, daily work is more about maintaining muscle memory, about remembering and cementing things students already know, rather than about learning new things and developing new ideas.  

* Be creative in holding students accountable.  Any assignment is useless if it's not taken seriously; any assignment, no matter how small, is useful if done with care.  Along with tapering comes the responsibility to ensure that students do the required work, and do it well.  Second semester seniors generally don't give a rip about their grades, especially if grades are used as negative incentive.  Use as many different positive incentives as possible.  I give exemptions from future work for particularly strong efforts.  I might announce an exciting activity like a physics walk, with the reminder that a complete assignment is required to go along.  Even small things like in-class music when everyone turns in the homework can help.

Whatever the incentives, though, be sure they are backed up with the inviolable requirement that all assigned work must be completed eventually and correctly.  Use every trick in your book to enforce this requirement, such that students recognize that it's easier and more fun to get the work done right and on time than to slack off.

* At some point, acknowledge the year is over.  Where that point begins is your judgement call.  But it's important, I think, to end the year on a high note.  I've had the class solder AM radio or robot kits; had them inventory and organize the lab; done the bridge building or egg drop contests... anything that requires no out-of-class effort.  

In late May, you're not teaching anything further to this year's seniors.  Instead, you're laying groundwork for the future.  Think about what you want this year's class to say to next year's.  Students talk to each other, and it's usually straight talk.  You want a reputation right in between "pushover" and "arsehole."  After a couple of years, that reputation will by itself minimize hostile relationships with seniors, as they will come to your course from the start with the expectation that the spring will be serious yet fun.  

13 December 2014

AP in-class laboratory exercise: Energy (And more on different approaches in 9th and 12th grade)

Above is an example of an in-class lab exercise for AP-level seniors
When I introduce a new topic in 9th grade conceptual physics, I hand out a sheet with a few facts and equations, then I dive directly into guided laboratory exercises.  You can see one set of such exercises, about collisions, here

I don't do any discussion, or example problems, or anything at all with me talking to the class. There's no point -- the freshmen don't have the attention span to listen, and they don't have the abstraction skills to apply what I show them to future problems.  Therefore, the 9th grade in-class laboratory exercises walk the students step-by-step through the solution to a problem, then guide them through the experimental verification of their solution.  No one can tune me out, because I'm not talking. Instead, each student himself has to wrestle with the problem, showing me his answer to each step. When someone does a step incorrectly, I help him, and send him back to his seat to try again.

When I tried the same approach with AP-level seniors this year, it didn't work.  

A freshman who's told his answer is wrong generally looks sheepish, goes back to his desk, does the problem right, and finally looks happy as a mollusk to move on.  

A senior takes the wrongness of his answer personally.  While the freshman just accepts my word that his answer was wrong, the senior tends to make ever-more-ridiculous arguments at me to justify his incorrect reasoning.  Seniors aren't sheepish about wrong answers; no, they're defiant, as if it were my fault that the universe doesn't work the way they want it to.  

On the other hand, I've had good success over the years holding seniors' attention with quantitative demonstration lectures.  So after Thanksgiving break, I went back to my previous approach in teaching the work-energy theorem.  It went well... I raced through a bunch of energy problems at the board over just a few days.

Then, after those few days of me solving problems and showing demonstrations, after a few days of problem solving on each night's homework, I handed out this in-class lab exercise.  

Each student got a different sheet.  The picture above shows problem 1 -- but the link includes seven different sheets, with seven different energy problems.  Three involve carts on a track, three involve objects on vertical springs, and one involves a sliding block.  Each problem requires students to solve in variables, then use semi-quantitative reasoning to produce a prediction.  The experimental verification can be done with motion detectors and/or photogates -- no other equipment required.

The seniors did much, much better this time.  They were no longer hostile -- they felt like I had shown them how to solve the problems, so that if they got something wrong, it was their own dang fault.  

And that was interesting... the freshmen never worried about blaming themselves or me for a wrong answer -- it was just wrong.  The seniors got very snarky if they felt that I hadn't showed them the correct approach at the board, or if I hadn't mentioned all relevant background information out loud in class.  They pouted at their seat if they were turned back more than once to try again.  

But once I had done my duty lecturing at the front of the room, the seniors enthusiastically took to the same kind of open-ended independent lab exercises at which they had thumbed their noses earlier in the year.

I will likely come to some broader conclusions about seniors in the new AP course after I experiment a bit more with my class this year.  I'd love to hear other teachers' experience with these or similar in-class exercises.  

03 December 2014

Using cell phones in class -- Socrative

My school today legitimized the (responsible) use of cell phones on campus.  In honor of that momentous event,* I posted the following to our faculty folder.  I first found out about socrative through AP Physics consultants Dolores Gende and David Jones, so thanks to them... hope you consider using it, and I hope that your cell phone never rings during assembly.

* which produced a level of rejoicing on dorm more appropriate for the destruction of a Death Star

Hey, folks... in the spirit of sharing, consider checking out "socrative" via  It's a free service that uses cell phones or any web browser as "clickers" for classroom surveys, questions, and quizzes.  Students respond to the questions on their phones, and the results are aggregated on the teacher's page so that they can be projected on-screen.  For those of us of a certain age, think of it as the ending to America's Funniest Home Videos where they polled the audience about their favorite, and displayed the results -- just using cell phones.

At the site, log in with your gmail account, or create a unique socrative account.  Tell it to ask a "quick question."  The website displays a room number, which students enter on their phones; then the students can participate.  (The students do not need an account.)  This sets up for use the first time in about two minutes.

I don't always use clickers.  But when I do, I use socrative.  (At least, I do now that cell phones are ubiquitous.)


01 December 2014

Teaching semi-quantitative reasoning: first, ask students to derive a useful equation.

Two identical arrows, one with speed v and one with speed 2v, are fired into a bale of hay.  Assume that the hay exerts the same friction force on each arrow.  Use the work-energy theorem to determine how many times farther into the hay the faster arrow penetrates.

Typical students know how to apply the work-energy theorem if the problem is stated in numbers.  In fact, if you told these students to answer this question by calculating the distances penetrated by a 10 m/s arrow and then by a 20 m/s arrow, they'd get the answer right.

But if those students try to solve in variables only, without making a couple of calculations with made-up numbers, they get lost.  They don't know where to put the factor of 2... they solve for v rather than for the distance penetrated... they get lost doing random algebra.  (Don't believe me?  Try assigning this problem.)  Nevertheless, I need to teach even my not-so-mathematically-fluent students how to answer this type of question with algebra rather than numbers.  

The trick, I think, is to rephrase the question.  Consider this version:

Two identical arrows, one with twice the speed of the other, are fired into a bale of hay.  Assume that the hay exerts the same friction force on each arrow.

(a)       Use the work-energy theorem to determine an expression for the distance into the hay that an arrow of speed v will penetrate.

(b)       How many times farther into the hay will the faster arrow penetrate?  Justify your answer.

When I explicitly require an algebraic solution for the relevant variable -- the distance penetrated -- in terms of the variable v rather than 2v, the question becomes straightforward.  Students see that the speed v appears in the numerator, and squared; so, doubling v quadruples the penetration distance.

The difficult part of the problem was figuring out to solve for distance in terms of v.  So I've told them to do that first.  As the year goes on, I will gradually take off the training wheels, and ask the question straight-up, like at the top of this post.  However, I want to start establishing good habits of answering problems involving semi-quantitative reasoning, so I'll guide students to deriving a useful equation first.