Trip, I would agree with you complety except I have taught this time of year when it is so difficult to keep the students attention.
It is so close to the end, why not have it done the afternoon after the last day of school?
Put your own kids, grandkids in that classroom. One person seeing it, makes no difference, because soon they will all know. The teacher is trying so hard to get the finally teaching in before finals. She can't do her job because of the distraction, and your child, or grand child does not do as well. Who's fault is it? Who suffers?