Yossarian is right. It's a indoctrination into a set of national ideals. The kids wear uniforms, march around with flags, get medals, and it ties this indoctrination into nationalistic fervor into the pre-dominate judeo-christian culture. It's become somewhat more PC and about camping, conservation etc since the 60s and 70s but there is no doubt that it's basis is a childhood introduction into the rigors of national military service.
It's a relic of a bygone era, the 20th century, like Hitler Youth or the Young Pioneers. I'd be surprised if many kids outside of the remnants of WASP culture participate. Maybe a few urban charity cases that get some kind of funding from it or something.