This all assumes the stance that nudity is immoral.
If you saw my porn collection, you would understand that's not my position. I am a huge fan of nudity, and don't think it's immoral at all. I wholly support a person's right to get naked, or in these teachers' cases, semi-naked.
As a matter of fact, the photos themselves are generally tame, and you can see worse at any beach, shopping mall, reality TV show, etc. It's not about the nudity. It's about the message it sends to young girls, and even to the boys who are now going to be popping chubbies in their classes instead of paying attention. I know that the "objectification of women" argument is kind of tired, and even mainstream women are saying that they're proud to show what they have and be beautiful. And I for one am 100% in favor of that. But I think that in an era when kids are being bombarded with mixed messages about sex, it'd be nice if at least the teachers could set a better example.
I guess I'm on my own on this one.