I was also disturbed by the naivete and thoughtlessness of this teacher, and I did email Casey at the contact address more than a week ago. This was a strongly worded message which mentioned not only how the kids could be harmed, but how Ravelry could possibly be held liable if something bad happened.
As of today, I have not received a response. The group still exists, but there are only three posts on it, and the last one was more than a month ago. So it seems to have fizzled as a classroom activity, but I still think the teacher needs a lesson.
BaaBaa on Ravelry