DOZENS of U.S. teenagers mixed cement, poured foundations, and laid pipes and cinderblock walls in impoverished communities near Lake Arenal, in north-centralCosta Rica, and Caño Negro, near the Nicaraguan border.They worked, rode horses and zip-lined through the forest canopy by day and discussed the geology, labor and political climate of Costa Rica before bed. It was a strange brew of education, vacation and community service. And the teenagers didn’t just fall for it – they spoke more eloquently about the bricks they laid than about the caves they spelunked.They arrived under the guise of kids on vacation with an international education and adventure company newly established in Costa Rica, Rustic Pathways. They chose one- or two-week programs, sometimes extending them longer with Spanish studies or linking programs in a custom-made grab bag of Costa Rican adventures. They chose from among programs with names such as “Soccer and Service in Costa Rica,” “Turtle Conservation Project,” and “Surf the Summer” – 12 variations in all.Rustic Pathways leads young people on educational adventures around the world, taking them scuba diving or four-wheeling, to ski slopes or on elephants’ backs, and teaching turtle and rain-forest conservation, photography and Spanish, among other things. It operates in Australia, New Zealand, Fiji and Thailand, in addition to Costa Rica, and will open operations in India and China in the next two to four years.The teenagers in Costa Rica sea kayaked, river rafted, surfed waves from the mellowest to the most board-bashing, and explored volcanoes, rain forests and mangrove swamps throughout the country. By the time summer vacation was over, some had built a home for rural schoolteachers in a lakeside village near Arenal Volcano, fortified a slope against erosion that was creeping in on an Environment Ministry (MINAE) outpost in the region, and built a community center in Caño Negro.NICK Ford, a typical non-conforming 17-year-old who sometimes wears women’s jeans, has a golf tee piercing each ear, puts himself in yoga poses in public spaces and listens to the concoctions of obscure DJs he downloads into his iPod, spoke unabashedly about how “good” it felt to move rocks. Last month, he and the others in his crew moved literally tons of large river stones, carrying them by hand and in wheelbarrows to fill the wire cubes stacked to retain slopes against erosion. The eroding slope was already lapping at the entry to MINAE’s future event center near Arenal Volcano.A few days later, Ford mixed cement and laid a cinderblock wall for the teachers’ home in the village of El Castillo. The week before, he had helped pour a foundation for the center in Caño Negro.“Last week we were just mixing cement, and that didn’t feel quite as fulfilling as what we are doing now. We put on this whole top row today,” he said, pointing to the top level of bricks.The cement wasn’t a winner among the volunteers; it was the sense of accomplishment and the sheer excitement of traveling here that garnered the most praise.THE lessons were varied. Some students, including Yelena Kneller, 17, learned about subjects as disparate as a foreign language and inefficiency in rural Costa Rica. She explained the work of cement mixing: “It basically took weeks to do what they do in the United States in a couple of days.”The week before, she had studied Spanish in a school in the Central Valley, adding some words in a third language to her fluent command of Russian and, of course, English.Before bed, those who worked near Arenal gathered in MINAE’s event center, where they stayed for the week, and entertained themselves with word games and puzzles. A couple or two sitting close signaled the new romances the week together had kindled, and, judging by the free interaction between nearly everyone present, that time had also crumbled the social factions famous in high school.Gabe Porter-Henry, trip leader for one of the groups that went to Arenal, closed the days with a mini-lecture and conversation starter, explaining the geological forces that created the stalactites they saw in the caves and the eruptions of the nearby volcano, and asked about the value of the work they were doing.“We try to help them understand what their connection is to the people down here or in other countries,” Porter-Henry said.“(We try to) understand economic connections between the United States and the world and specifically Costa Rica.”EL Castillo is a young village on the new lakeside – its founders 35 years ago were the displaced inhabitants of riverside towns before the river was dammed and flooded the valley, creating what is now Lake Arenal.The volunteer youth visited the schoolhouse twice over the week, once to teach English to the elementary-school children, and again to build a house for the teachers and paint one of the two school buildings. The schoolhouse is 20 years old, built by the people of the village without government aid, director Jaime González said.The last addition was completed last year: a seventh-grade classroom that will become a single-room high school as the students progress.“It is the product of a poor community that works hard,” González said.The elementary-school children have practiced traditional synchronized dances and wear old dresses donated for practice.They needed proper uniforms, both for the boys and the girls, and new shoes. The visiting volunteers decided to pool their money, each donating about $20, to give the children nearly $300 for 12 uniforms and pairs of shoes.CHRIS Stakich was instrumental in pioneering Costa Rica as a Rustic Pathways destination. A recent Harvard graduate with a degree in economics, he approached the company hoping for a means of blending his business savvy with two loves – education and travel.“From studying abroad and traveling to more than 20 countries, I already knew that international travel is the world’s best classroom,” he said. “It provides perspective, compassion, and it will humble any human being.”With today’s rate of globalization, he said, it is crucial to have a young generation indoctrinated in compassion toward foreigners.“We are not the only country on the planet; we are not considered ‘number one’ by most countries, and we must realize that other countries have beautiful areas with wonderful people from whom we can learn a lot,” he said. “My hope is that by visiting towns like El Castillo and others, Rustic Pathways students will open their eyes and realize that the world is filled with wonderful people.”Extensive information on all of Rustic Pathways’ programs is available at www.rusticpathways.com.