K.S.
I know you already got great responses (well, mostly, a couple of them- yikes, sorry you were subjected to that). Anyway, I always thought that volunteering would be great to see what happens in the classroom, but then I realized that sometimes seeing so much is not a benefit! No teacher will ever do everything you wish for them to do. Sometimes ignorance is bliss! If it were me, I would let this one slide, but just keep my eyes and ears open. I'll bet in a week or so you'll feel like this isn't worth mentioning, unless it keeps happening. Good luck!