On a rocky trail in South Dakota's Black Hills, granite spires towering above him, Alec Walker had a moment of rare personal clarity. It was the spring of 2004, and Walker, a junior at TrekNorth High School in Bemidji, Minn., had sidled up to his science teacher for an ad hoc geology lesson during a hike.

They examined quartz crystals and feldspar, an expanse of granite tumbling ahead and out of sight.

"I realized I could do this for the rest of my life," said Walker, now an aspiring geologist and third-year student at Michigan Technological University in Houghton.

Field-based epiphanies are a hallmark at TrekNorth, a public charter school where outdoor adventure is regarded as a pillar to learning. The grade 7-12 school, which has 165 students and 13 teachers, is in a strip mall off Paul Bunyan Drive. But it runs its extensive Outdoor Adventure Program to corners as far afield as Alaska and the Appalachian Trail.

The completion of a high adventure -- from mountain climbing in Washington's Cascades to backpacking a section of the Superior Hiking Trail -- is a requirement for each student before graduation.

"Wilderness trips are a catalyst for integrity, confidence and leadership in kids," said Dan McKeon, the school's executive director.

McKeon came to TrekNorth as an English teacher when the school opened in 2003, working his way up to become director three years later. A lifelong outdoors enthusiast, McKeon has roped up TrekNorth students to climb 200-foot-high formations in the Needles of South Dakota. He has run dozens of trips, including paddling to far reaches of the Boundary Waters Canoe Area Wilderness for eight days at a stretch.

He said students gain through day trips and expeditions by building traits impossible to achieve with chalkboards and books. "Students learn on trips that they are tougher than they realized, and can do more than they ever thought possible."

The student-teacher relationships formed on wilderness excursions are authentic and strong, McKeon added.

Alec Walker concurred. "After a trip, you feel comfortable talking to your teacher about anything, and you are friends," he said. "Then you want to do good for your teachers in class -- it's a huge motivator."

A top public high school

Walker, who was not outdoorsy before enrolling at TrekNorth, said he would wake up during his high school years excited to go to class.

Beyond backpacking and scaling rock walls, TrekNorth requires a traditional class load -- math, science, social studies and reading included. The school is governed and funded the same as any public school. Its teachers are licensed by the state.

Advanced-placement (AP) classes, which can count toward college credit, are encouraged at TrekNorth, and most juniors and seniors are enrolled in one to three AP courses each year. McKeon notes that U.S. News & World Report magazine has twice named TrekNorth a "top public high school."

A third focus at TrekNorth incorporates volunteer work and community projects into the curriculum, with students assisting at area nursing homes, working at soup kitchens and preparing packages of food for a charity focused on Third World nations.

For students like Carrie Miller, a senior who transferred from Bemidji High School in 2007, TrekNorth's nontraditional learning environment is a draw. On trips from northern Minnesota to the Appalachian Trail, Miller said, TrekNorth has changed the way she looks at the world.

"I used to really care about clothes and what other people thought about how I looked," she said. "I've discovered there is so much more to life."

Miller, formerly an aspiring fashion designer, now says she's interested in an environmental career -- "maybe sustainable agriculture," she said. Close bonds with teachers and fellow students, Miller added, have made her time at the school meaningful. "You develop connections not possible in most other settings."

She tells the story of a trip last fall on the Appalachian Trail when she and a classmate were struggling with blisters and a slow pace. It was near sunset, on a mountainous section of the route, and that day the group had trekked more than 15 miles with heavy packs.

Miller and the other student -- a new classmate she didn't know at the time -- switched shoes. They finished the hike together, blisters hurting but more manageable, as the hills were growing dark.

"When you literally see your classmates struggling to climb a mountain, you learn to help each other out," Miller said. "Then you come back to school and the whole class environment has changed."

Stephen Regenold writes on fitness and the outdoors at www.gearjunkie.com.