Mail time: AP laboratory questions using "equipment usually found in a school physics laboratory"

A post to a physics teaching message board asked the (paraphrased) question:

I was wondering about "design a procedure" AP Physics questions that ask students to use "equipment usually found in a school physics laboratory".  What are the limits here?  Would readers take off if a student used, for example, an accelerometer?

An accelerometer is fine.  It's available in the Pasco/Vernier catalogs and on smartphones - that's way common enough for me!

In general, I wouldn't stress about what's "common" or not.  No one is lawyering up about "well, this is only used in 49.1% of high school physics classrooms, so minus two points from Gryffindor."

Much more importantly, make sure your students can (very briefly!) in their procedural description show that they know how the device is used.  "Plot acceleration as a function of time using an accelerometer mounted to the cart" makes sense.  "Carry a phone on the roller coaster, and look at the acceleration-time plot using the built-in accelerometer."  Those are fine.

"Point the accelerometer at the cart to get its acceleration" doesn't work.  :-)  An accelerometer isn't a radar gun, nor is it a magic wand*.  I often see this issue with e.g. a photogate - it's not a point-and-click device! 

*Using it as such *would*, in fact, result in minus two points from Gryffindor.

Similarly incorrect would be, "Launch the ball from the projectile launcher.  Use an accelerometer to get its acceleration during the launch."  Now, I suppose you might be able to crack open the ball, insert a miniature accelerometer, paste the ball back together, launch the ball... but no.  That's not at all "common".*

* If someone truly did go through all this description, though, the procedure works.  Way ridiculous and time-wastey, but would such a student show comprehension of experimental physics?  I'd say so.  Point is, just saying "use the accelerometer" in this case isn't good enough for the readers to infer this farfetched procedure.  But if they write out all this detail, then sure, they have demonstrated serious understanding.

A diagram can do the work of the words here, too.  If a student shows the accelerometer attached to a cart, or a phone mounted to a cart or something, then it's clear the student understands what an accelerometer is and how it works.

Hope this helps!

Greg