In this post, I said that "When in doubt, assume that a student's question or suggestion is sincere." Here's an example where I did not follow that advice and regretted it:
Once, when I was a TA for an intro to US history (part 2, from the Civil War to the present), we were discussing the 1970s in discussion section. I mentioned "stagflation" and defined it as "a recession in which there is inflation instead of deflation." I drew a contrast (if I recall correctly) between the 1970s and the Great Depression and the Depression of the 1890s.
This was in Spring, 2008, at the beginning of the present recession, and one of my students asked, does that mean we have stagflation today? I quickly dismissed the question with a comment, the gist of which was "no, this recession is different."
I was wrong to be so dismissive. She was one of my brightest students, but even if she hadn't been, her question was sensible: newspaper accounts (and for all I know, economists) were reporting that we were in a recession and that we had inflation. Ergo, by my definition of "stagflation," that's what we were experiencing. (This was before the credit crisis had hit its nadir, so the possibility of deflation wasn't in the news.)
What I should have done is acknowledge that my definition of stagflation might be faulty, because I doubt that even the more alarmist economists in 2008 would call what we were going through a "stagflation."