Hooray! This seems to work the way I want it. It is allowing me to send stuff to kids outside of class that they will actually see, but I don't have to deal with the potential over-sharing of friending them. I'm testing it out with one class for the remaining few weeks of the year. Here is what I did:
1. I explained the purpose to the class. They liked the idea and were very helpful with some setup decisions. I passed around a sign-up sheet for students to provide their email address, strictly voluntary. 15 out of the 20 students present signed up.
2. I went to Facebook and created a new page. I set it to Local:Education and called it "Dispatches from Ms Nowak" which I know is a lame title but it's descriptive enough.
3. I uploaded a picture and set some other settings the way I wanted. In the "about" section, I encouraged them to use the Wall for public communication with me and each other, but use my school email address for private communication with me. Then clicked "Publish Page".
4. I sent a mass email to the students who signed up (using Bcc: so they didn't all get each others' addresses) with a link to the page. It's up to them to go there and "Become a Fan."
5. Once they are fans, they will get updates in their news feeds when Wall posts are made on the page.
Ta da! I think this is everything I wanted. I can get their attention in their communication medium of choice, but all the interactions are publicly viewable, and the only pathway for private communication is the school-sanctioned one.