As happens from time to time, even in summer, I was recently eating lunch 'al desco'. While I was eating-working, a student walked in my office to ask me a question, saw I was eating lunch at my desk, and said "Oh, I'm so sorry for interrupting your lunch. I'll come back later."
I was stunned. This has never happened to me before. In my experience, no student has ever before acknowledged that eating lunch @ one's desk means one is busy and therefore perhaps non-urgent questions can wait until another time.
I already had a very high opinion of this student, but he shot up even higher in my estimation after this incident.
Alas, his polite response to seeing me eating @ my desk makes him a rare beast indeed.
Memo to visitors: If you walk into someone's office and see them eating lunch at their desk, this probably means they are busy. If you aren't sure and ask "Are you busy?", this is more polite than not asking, but this question, however well intentioned, might elicit a glare, an incredulous laugh, sarcasm, or insincerity (just so you know).
I certainly can't speak for all professors -- perhaps there are some who so love their desks and offices (and office chairs!) that eating@desk is a pleasurable activity that is done by choice and that has the added benefit of attracting cute little rodents (and insects!) -- but I typically eat at my desk if I am so busy that my only other option is to skip lunch.
Lunch-skipping occurs now and then too, but it is not a good idea if I am teaching an afternoon class, and dangerous if I have an afternoon faculty meeting.
Yes, I know that I could close my door. I have tried that, but then people knock and I either have to get up and go to the door to tell the visitor(s) that I am busy, pretend that I am not there even though it might be obvious that I am (causing emotional trauma to some, as I have learned from experience), or yell Go Away I Am Busy.
I once tried a Do Not Disturb sign, but some people didn't see it and knocked anyway, some saw it but wanted to know why I didn't want to be disturbed, and others told me later they thought I was probably taking a nap in my office. So maybe I need a Do Not Disturb Because I Am Really Really Busy Right Now and No I Am Not Sleeping sign.
I find all of these options less appealing and more time-consuming than having someone step into my office, ascertain that I am busy, and go on their way until another time when I am not in simultaneous mid-chew and mid-something-else.
None of this is a big deal, of course, and it doesn't punch a hole in my day if I encounter someone who starts talking to me without even asking if this is a good time to interrupt, but when I encountered a real live polite person this week, I realized how nice it was to have such an experience for a change.
That said, it's time for a poll:
1 year ago