There is a program here in Colorado Springs called 'School In The Woods'. It started in 1999, until this year this program only took 52 4th graders, now it has expanded to 78 4th graders.
The school is in Black Forest (this is an area in Colorado Springs and has been called this longer then I've been alive because of all the trees), anyway, the school has 640 acres that is used as a living classroom.
It's only for 4th graders and they learn everything about the environment. They check wind speed and temperature, they study insects and plant cycles.
It was designed to increase students knowledge of natural science. I really wish they would have had that when I was younger, it would have been so interesting.
If you want to read more about it, the article is by Kristina Iodice, 'Window To The Outdoors Will Push Open Wider', www.gazette.com