#3 - I like quite a few elements of this design. I like the compass and that you took time to include some graphics of what we do. You can get a better idea of our camp here:
http://www.actionwhitewater.com this is my rafting company page and within you'll see plenty on the camps and what we do.
I like that you worked to build in our slogan. I like the colors in the compass. I like the hyphen in the name. I like the two tone nature of the font, my initial idea was a brown/beige with a forest green outline, here you went white with black, the concept is the same and I think it helps the name jump out. I'm not sure if it MUST be this way but it was my initial thought too.
**I had a thought after looking it over again and again. Could you mock something up with the words Nature's-Classroom curving around the upper half of the compass and put the slogan in the smaller font at the bottom. Perhaps in the East and West areas of the compass you could put a graphic of a absailer/rappeler and then a river otter or beaver or California Black bear in the other. This would cover 4 major elements of our camp in graphics.**
I DON'T like the font itself here, I think it get's lost in the compass. This logo will be on shirts, hats, letterhead, business cards etc. I don't think Script is the font style to use. I like the font of #2 quite well or at least the effect. It's bold and very clear what the name of the company is. Overall I rank this one as my current favorite of the 3 currently submitted.