KAILUA — When the fourth-graders of Kailua Elementary School raise money for their annual Big Island trip, they also raise something else: their knowledge of old Hawaiian ways.

Instead of selling the usual tickets for chili, candy or cookies, the students help pay for the trip by building an imu, or underground oven, where pigs, turkeys and other meals brought by family members, friends and community supporters are cooked.

As the imu is opened up this morning on the school grounds and the food is distributed, some of the kids will be there to take satisfaction in a job well done. Some of them might even have some sore arms.

Yesterday about 40 youngsters from the school's two fourth-grade classes pitched in to erect tarps, hammer tent pegs, set up tables, prime the fire pit and form a long, snaking fire-bucket-type line to bring the imu rocks, ranging in size from baseballs to bowling balls, from behind the school to the pit in front.

They attacked each task with the unbounded energy that you can only find in an elementary school group freed from the confines of the classroom for the day. "It beats language arts class," one of them said. Whether they knew it or not, though, they were getting important lessons in Hawaiian culture and concepts of shared labor.

"Laulima. That means many people sharing the work," teacher Linda Elia said to anyone who would listen as 80 hands helped hoist a tarp over the area where arriving food would be stored before going into the imu. "Huki. Pull."

Later, as fellow teacher Dan Haiola supervised the rock line, making sure no fingers got smashed, Elia explained that the third annual school imu started as a fundraiser for the trip, but that teachers also incorporate its lessons into the curriculum.

"A lot of what they're doing teaches the values of everyone working together, sharing the load," she said. "They're experiencing firsthand what the ancient Hawaiians had to do to cook the food or build a heiau." Even the students who won't be able to go on the Big Island trip for one reason or another, she said, get into the spirit of sharing by selling imu tickets to help their friends, she said.

"Teamwork is good or else you don't get anything done," said 10-year-old Matthew Campbell, who had never seen the work that goes into an imu before.

"I learned that back then it took a lot more hard work to do the cooking," added 9-year-old Logan Rash, still dripping with perspiration from carrying rocks.

Todd Hendricks, a retired Kailua High School teacher who has been building imu as a fundraiser there for 10 years, brought the idea to the school three years ago, when his grandson was in the fourth grade.

"They're learning by doing. The teachers mix this hands-on work with a writing project, but it's the sense of shared labor that they'll remember all their lives," Hendricks said.

This year about 150 people paid $10 each to have a pan of their favorite food cooked in the imu. The three-day trip to the Big Island is set for May.

Reach Mike Leidemann at mleidemann@honoluluadvertiser.com.