I don't think I've seen "Boston Public" mentioned. The teachers are mostly lower/middle class and as are the students. It takes a really good look at what working adults with a lower income have to deal with, and how teenagers growing up with less options deal, I think. There's also "Teachers".
Another British show would be "Skins". Some of the characters are privliged, but because the show constantly changes POV you get to see a lot from the lower class characters lives as well.