I think everything has already been said....so I will just say I agree. I can not even begin to imagine a child doing that in my class! There are several ways the instructor could handle this, and not doing anything is not one of them.
If you don't want to stand out to complain, perhaps you could slip an anonymous note in her mail box or bag?
OR if you do want to stand out, start a petition and get everyone to sign it!
Just kidding!