A couple weeks ago when I was caching over near Spartanburg SC I ran into a really neat idea for an outdoor classroom while doing a virtual cache.
The place is called South Carolina Academic Learning Environment, or S.C.A.L.E, and I am not sure if that name refers to the outdoor classroom or a larger initiative.
The classroom is a wood area, several acres in size. It is laid out to resemble the state of South Carolina, with paths laid out like Interstate highways, creeks like major rivers, and learning areas with benches where cities would be. Along the way markers listed what each item represented, and they even had highway markers for the foot paths.
It is a simple idea, but one of the neatest things I've seen in quite some time. Certainly an interesting way for a student to gain familiarity with his home state. I'll leave you with a couple more pics.