Traditionally we tend to think of "green schools" as though that recycle, use wooden toys, and teach our children about the environmentally friendly way of life. In one sense though, we're missing an entirely separate entity of what the term can mean. To me, online schools are another eco-friendly school.
An online school conducts all of their correspondence via e-mail meaning no trees are harmed in the process. Also, many of the lessons are also conducted over the internet meaning there's even less trees wasted there. Not only that, but because students can take these courses from their own home, there's no gas or emissions wasted driving to or from school.
Have you ever thought of green schools this way?