I’m in the middle of marking exams for a course and have had a few suprises.
It’s pretty common for students to interpret or tackle a question in a way you hadn’t foreseen, and this is fine, you err on the side of the student. What I’ve just realised is that you shouldn’t offer life tips as part of the question as the context can got spectacularly awry:
I had a question examining a beam from a 1mW laser pointer entering the eye for the duration of a blink. Things like how much energy was transfered etc, then finishing with how the intensity compared against the image of the sun on a summers day. I finished the question with “NB though this value is high it does not appear to cause lasting damage for exposure within the blink time (0.25s), so laser pointers are usually classed as safe”  (they’re a bit touchy about laser pointers here in NSW).
What I hadn’t counted on was some students interpreting mW as a mega-watt and therefore tacitly assuring them they could look into a megawatt laser … hmm, maybe I should have said it would not cause lasting damage, again.