Howdy! I've spent the last week grading, and training people to grade, the lab problem on the 2016 AP Physics 1 exam. I'm a bit punchy, as you may expect. Nevertheless, I encourage you to apply to be a reader -- I really, really love the people I meet here, even if I'm not always entirely enamored of grading papers for eight hours a day.
Part (a) of our question asks for a description of a laboratory procedure. It could be answered in 20 words: "Use a meterstick to measure the height of a dropped ball before and after it bounces. Repeat for multiple heights."
But oh, no... when America's physics students are asked to describe a procedure, they go all Better Homes and Gardens Cookery Manual on us. Folks, it's not necessary to tell me to gather the materials, nor to remind me to first obtain a ball and a wall to throw it against. Nor do you have to tell me that I'm going to record all data in a lab notebook, nor that I'm going to do anything carefully or exactly. Just get to the point -- what should I measure, and how should I measure it.
Please don't underestimate the emotional impact on the exam reader of being confronted with a wall of text. We have to grade over a hundred thousand exams. When we turn the page and see dense writing through which we have to wade to find the important bits that earn points, we figuratively -- sometimes literally, especially near 5:00 PM -- hit ourselves in the forehead. Now, we're professionals, and I know that we all take pride in grading each exam appropriately to the rubric. Nevertheless, don't you think it's worth making things easy for us, when we be nearing brain fatigue? Just as good businesspeople make it easy for customers to give them money, a good physics student makes it easy for the grader to award points.
Don't think I'm making fun of or whining about students here. Writing a wall of text where a couple of sentences would suffice is a learned behaviour. The students taking the AP exam are merely writing the same kinds of procedures that they've been writing in their own physics classes. It is thus our collective responsibility as physics teachers to teach conciseness.
"Okay, Greg, how do we do that?" I hear you asking. I have a two step plan.
(1) Give the students a word or sentence limit, and hold them to it. For virtually any AP Physics 1 procedure, three sentences will do. When your students list a twelvefold process, award no credit, and don't give in to the subsequent whining.
(2) Don't ever award credit for baloney. When students have one nugget of valid description buried in a mountainside's worth of muck, just stop reading and award no credit. The burden of proof is on the students to convince you they understand the methods they describe. It's tempting to yield to after-the-fact whining and lawyering: "Well, if you really think about it, the meterstick could measure force if..." No and no.
Fight the clarity and conciseness battles in October; then in May when your students take the AP exam, communicating experimental methods will be (a) easy and (b) quick.