Possibly some of the kids may belong to households where there's a computer, but no reliable internet access (probably not, though, if you're in a high-tech area). However, in that case, PDF Wiki articles might be useful for offline reading.
The Creative Commons Wiki has a
listing of CC-licensed books. It's as they say, quite incomplete, but it gives you something to start with, and they've got a blog keeping up with professionally published people now
releasing selected works as CC.
One of them happens to be Canadian science fiction author Peter Watts, who's just won a Hugo Award for his novella
The Island, and puts practically everything of his CC-licensed
up on his website. However, he tends to be fairly sharp and cynical in his writing, and thus might possibly be considered age-inappropriate for US teenagers in much the same way that the likewise CC-licensed
Cooking With Booze would be.
I'd also consider taking advantage of the US' slightly weird public domain rules, and go looking on Project Gutenberg or the Internet Archive for that copyright-not-renewed pre-1963 stuff and see if there's anything that looks like it might be interesting. It'll at least be a little more modern than the regular Life+70 selection.
And speaking of copyright and the public domain, there's probably no better way for the kids to learn about how various corporate interests are encroaching upon it and eroding fair use than via the
CC-licensed comic book produced by Duke University's Center for the Study of the Public Domain, free to download and distribute in PDF, or remix in jpg or png to your heart's content.
You can get it in French, too, in case someone wants to use it for their language lessons.