A school, a commune, a traveling road show, a family going from Woodstock (N.Y.) to the Yucatan, getting off on ""truckin' consciousness,"" reaching out to shake hands with ""planet brothers and sisters"" -- that's the True Light Beavers. They began, as they will tell you, with only a dream and a lot of stored up dissatisfaction with public schools; they became a parental-cooperative free school in Woodstock; some Earth Peoples Park builders came up to construct facilities -- ellipsoid geodesic domes not yet completed. They are, as you may have surmised by now, the extreme left-wing fringe of the free school movement -- libertarians striving for ""synergetic"" education a la Bucky Fuller, and away with notions of mine and yours, WESTern civilization and ""My Daddy can beat up your Daddy."" They believe in learning by doing, seeing, feeling and experiencing -- the last in great oceanic waves of brotherhood and sharing. They're very casual about reading, writing and arithmetic and report that after three months of testing their new freedom by nonstop play, the kids started real lessons on their own accord -- though the content as described here is very nebulous indeed. The Mexican junket (while waiting for the domes to go up) involved a van, six adults and four children and the book is their collective journal notes of the trip -- what to pack, how to rig the van, how to deal with border authorities, Mexican highways and machismo -- what every tourist should know. All the way to the Yucatan they keep on truckin, mama; once there they visit Mayan ruins, meet Mexicans, and commune cross-culturally when not being ripped off or getting diarrhea. The experience sounds idyllic enough but, like those domes, inflated out of all proportion to real educational value and filled with hippie homilies on having the courage to live your fantasies, making do with much less material effluvia, and feeding your soul on sunsets and stars and good vibes.