Dear Bob: As a first year teacher I don't have too much experience to draw
from, and as a teacher of k-2, I have not come across this specific problem
however sometimes the students will come out with an inappropriate
comment, sometimes I think they aren't even aware what they are saying.
When this happens I say, excuse me, this is an art class. We talk about
art here. If you can't say something nice, don't say anything.Good luck,