and take a deep breath.

Instead of sending them a letter immediately, I would go talk to them straightly. I wouldn't give them the impression that I'm hurt and weak.

Maybe this is what can do this afternoon when you pick up your kid. Bring your digital camera with you. Make sure the teacher (who might be the person who posted the article) is present when you take it out from your purse. Before you take the picture, talk with the teacher (with big smile) maybe saying something like this, "I found this article very interesting, and it's even more interesting that it's posted in the classroon. Do you mind if I take a picture?" I'm sure the teacher will get the gesture. If she removes it immediately, good for her. Don't do anything further as everybody deserves a chance to correct their mistake (regardless what they really think). If not (maybe she was not the one who posted it), take a picture anyway. On your way out, show the picture to whoever is at the receiption desk (again with a smile), and tell them the same thing as you said to the teacher. Give them some time to correct it. I'm sure they'll take action.

If in two days they haven't done anything, pull your kid out. I think they'll ask why. Tell them that you don't think this not a good and the right environment for your kid, or any kid. Tell them that you heard certain places (name some names if you like) are better in this regard. Tell them that you may discuss on this with a local reporter you know and see what he thinks.

Bottom line, don't act like a victim. You don't want to give them the impression that you are weak, do you? In stead, let them feel that they are stupid. After all, there are ignorant people, and their stupidity is not YOUR fault.