What do my students have to do to get credit on the AP exam? (They have to *communicate*.)

We're in the time of year in which AP classes have discussed enough material that they're trying out more and more authentic AP questions.  And teachers are grading to authentic rubrics, trying to give students advice about earning credit.  

There is only one piece of advice your students need:  communicate clearly.

Should I teach my students to box their answers?  If you insist... but who cares?  If your student clearly communicates the steps toward the answer, the reader will follow.  

But if they don't communicate clearly, won't the boxed answer help the reader find the answer?  Maybe, but credit isn't always awarded for just the correct answer.  (In AP Physics 1, there's hardly ever a numerical answer, anyway.)  I strongly encourage teachers not to teach games or tricks.  Rather, insist on clear communication from the get-go, such that "always box your answer" becomes as redundant as reminding an opera star to project her voice.

What if a student uses notation different than our textbook?  Is the student clear about what they mean?  Then it's okay.  For example, some texts teach to call rightward forces "positive" and leftward forces "negative", then add the forces using signs.  Others suggest subtracting the right forces from the left forces.  Who cares?  If the student clearly articulates their approach, if the student is consistent and correct in applying Newton's Laws, that's all good.  The exam is graded by physicists, not lawyers - readers rarely stand on ceremony about a notational issue unless it makes the physics wrong.

But what if they lose a point because...

Relax!  All these sorts of hyper-specific questions from teachers usually boil down to a student complaining about losing points on an assignment.  We have to elevate the conversation so that we're not arguing about points, we're teaching how to communicate physics principles.

When your student has an authentic question about how you applied the rubric, or about the physics concepts underlying the rubric, certainly answer as best you can.  But read your student's body language.  When they roll their eyes and throw up their hands, showing everyone that teacher is pond scum who obviously is too stupid to hold a job; or when they use the wheedling tone of a car salesman suggesting they might throw in free floor mats if you'll award the point; stop.  Don't engage.  You're not going to win the argument.

Winning the argument isn't the purpose of the exercise.

I understand the difficulty of a teacher's position here... if you're not an AP reader, you are trying your dangdest to interpret official rubrics, and to apply them to responses that you're not sure about.  Where can you go for guidance?  You're looking for hard and fast rules, clear boundaries between right and wrong.  You must recognize that such boundaries simply don't exist.  Even at the reading we see edge cases, responses that are quantum superposition states of earning a point and not earning the point.  

The best advice I can give is to ask, "did this student clearly communicate a physically sound approach to the problem?"  If not, don't award points.  The burden of proof is on the student.  When in doubt, it's wrong.  

Now, don't be nit-picky... consider that the audience for the clear communication is an intelligent person with the same level of physics knowledge as the student.  

But at the same time, don't read in to what the student has written; don't let the student argue about what they meant to say.  It doesn't matter what they meant to say; we grade what they did say.  I've never yet, in 20 years of reading AP exams, had a student follow their exam around the reading rooms lobbying for points, telling the readers what they meant.  And so I don't allow such a thing in my classroom.

In the end, grading AP problems is like calling balls and strikes.  Do your best to establish a zone.  When it's close, call a strike without hesitation or second thought.  When someone looks at you funny, smile and move the game along.  As long as your zone isn't ridiculous, as long as you seem kind but firm, everyone will just shut up and play.  And that's what we came to the field to do, after all.