Three dozen sixth-graders have been learning history and other lessons from the inside out this fall, from the occasional booming cannon to the paddlers stroking down the Mississippi River from source to mouth.

They're inside Historic Fort Snelling, where two classrooms from Upper Mississippi Academy have been meeting since Labor Day in a barracks inside the reconstructed bastion that commands the junction of the Mississippi and Minnesota rivers.

"What an experience," said teacher Kelly Grucelski, who compared the feeling of teaching inside the fort to a one-room school. She's a humanities teacher at the fledgling charter school, and she teams with Sarah Oppelt, who is a science and math specialist.

The academy, in its first year, didn't set out to hold classes inside the reconstructed fort's walls. The school, which consists of sixth- and ninth-graders this year, drew more students than anticipated — too many to fit in the modular building most of its students occupy elsewhere in the Fort Snelling complex. Then the Minnesota Historical Society offered space in the actual fort, half a mile away.

The arrangement is temporary, ending Friday. The school has rearranged its other quarters to allow its two classrooms to return to the mother school. It plans to move to a permanent home in the fort's Upper Post, across from Officers Row, sometime during the next school year.

But that's in the future. This fall, the kids reveled in reading on the shaded front porch of their barracks or holding recess on the parade ground. In their classrooms, which were partly renovated by the Minnesota Historical Society for its programs, the past is as present as the crinkly leaded glass in the windows that supply much of the illumination on sunny days, and the present is evident in the wireless laptops the students plug into to complete assignments.

Fireplace alcoves at each end of the room offer cozy nooks for readers who curl up on oversized pillows. "We have a better deal than the other classrooms," said Julian Branden, whose only previous exposure to the fort was when his former school in Minneapolis took a 90-minute field trip there. He's an avid reader on fort history.

Joe Haupt, another student, feels a personal connection with the fort. Not only did he often bike by the fort on his way to his former school in Mendota Heights, but his great-grandfather passed though the Snelling post during Army Air Force training.

"I thought it was very cool, because there's nowhere else that the classes are in a historic site," he said.

Testing site for programs

Tom Pfannenstiel, the fort's manager, said the relationship offers the Historical Society a chance to test some of its programming for school groups. "There's been a greater community feeling out at the fort," he said.

Some fort activities have side benefits. When the fort set up for a pilot World War I commemoration in September, complete with a simulation of trench warfare and stations on topics ranging from chemical warfare to suffragettes, the kids studied the timeline and alliances that preceded the war's outbreak. They were ready when the re-enactors started firing.

"We heard the rifles going off," Grucelski said. Students scrambled to collect shell casings and created a brisk trade in them by the time the school day ended.

In quieter pursuits, students collect soil sample and record natural phenomena. They got to spend two days learning to pilot voyageur-size canoes to Hidden Falls and around Pike Island. They met and now track by GPS a group of young adult paddlers as their flotilla descends the Mississippi, supplying them with research reports on the towns where they land.

Part history, part now

There are complications in a setting that's part historical and part 21st century. To offset the fort's lack of outdoor lighting, the kids prepared 100 luminaria so their parents could find their way to the barracks after dark for parent night.

The teachers find that the school and setting fit their teaching interests. Grucelski was working at another charter school, helping students plan their transition to middle school, when Upper Mississippi Academy came calling. So many of her students were switching that she checked on the school and was drawn to its hands-on approach to learning.

Oppelt said she isn't the type of teacher to stand in front of 60 kids talking. "I'd much rather put a plate of worms in front of them and wow them with that," she said.

She recalls walking the gravel path into the fort one morning when a thick fog blotted out the visual clues that the fort is a historic remnant situated atop a freeway and next to an airport.

"Honestly, I was like it could be the 1800s."