I'm not writing about pieces of lab equipment; rather about "something that reflects changes in circumstances or opinions." So what's a student barometer?
From The Digital Cuttlefish:
Do you have them? They don’t show up every semester, so consider yourself fortunate if you get one, and powerball-level lucky to get two or more in a class. These are the students whose faces are an honest reflection of how well you have explained something. If you are less than clear, an eyebrow might go up, or a head might tilt just a bit. Another student might be nodding in agreement, but frankly, always nods in agreement, even if you are presenting the old, wrong, out-of-date view you are about to demolish.
But the barometer student is skeptical. Listens. Processes. Understands. And (most helpful to you) it’s written on her or his face. Just spoke with one of three such students this semester (lucky me!), who I would have sworn was lukewarm about this class. I could not have been more wrong (I blame cultural differences; this student was from overseas). Once again, I am a happy Cuttlefish. And a sad Cuttlefish, because this particular barometer (indeed, two out of three of this semester’s barometers) is graduating, and the odds are we will never meet again.
I suppose by this time in my career I should be accustomed to never seeing people again after becoming invested in their lives. Maybe I am, and the sadness is not strange, but simply an appropriate reaction to the situation. “Accustomed” does not mean “immune”.