SEARSPORT, Maine — Last spring, the students at Searsport District Middle School spent a couple of days in Stockton Springs digging test pits, searching for artifacts and learning how to correctly catalog their finds.

This week, the junior archaeologists learned that what they carefully excavated from the yard around a Cape Jellison home has real significance — especially a centuries-old coin that they found just before the dig came to an end.

“You guys came in and surprised me with what you found,” Paul Bock, a former archaeology field technician who now runs Stoney Knoll Archaeological Supplies with his wife, Sharon Catus, told the assembled students on Monday.

The couple has been excavating around their house since they moved in, but finding the copper Dutch duit from 1735 means that they can accurately pinpoint the time that local American Indians camped there, likely while engaging in the fur trade with European ship captains.

The site predates nearby Fort Pownall, which was established in 1759 to help the English keep the French and their Indian allies at bay, according to the Maine Department of Conservation. Although the French and Indian War ended soon after the fort was built, it continued to serve as a trading center in the region.

The coin may have had little monetary use for the Penobscot Indians, but they would have been able to use the raw copper for other purposes, Bock and Catus said. It also shows just how important and widespread trade was in the 18th century, even in the wilds of Maine. It was minted by the Dutch East India Co., established in 1602 to carry out colonial activities in Asia.

“What was it doing here?” Bock asked.

In addition to the Dutch coin, the middle schoolers found more than 12,000 other artifacts, which Catus and Bock said they’ve spent the winter washing. Most of those items dated from the 19th century, when two farmhouses stood on the ground located on a well-drained slope above the Penobscot River. But the really interesting material came from the 1740-1750 time period, an era when the Penobscot Indians were trading fish and beaver furs for iron tools, firearms, copper kettles, axes, knives, trade beads and more.

“We had hints of it before, but you guys really nailed it during the field school,” Bock told the middle school students. “So many times, we wanted to give up on this site. You did well. You did very well. Thank you.”

Catus said that when she showed photos of the neat test pits and careful documentation of artifacts done by the students to professional archaeologists, “nobody could believe it.”

The couple soon will publish an article about the excavation in the Maine Archaeology Society Journal, giving credit to the school, and its eager junior archaeologists, such as 14-year-old Micheal Freeman of Searsport.

“I thought it was really good,” he said. “I think it’s really interesting that we can find out what happened in the past.”

Catus stressed that what they did was more than collecting artifacts.

“With archaeology, it’s not what you find — it’s what you find out,” she told them.

Susan Capwell, a seventh-grade humanities teacher who also participated in the field school, said that the hands-on work helped to energize her students.

“They weren’t just digging for fun. They were really excavating a real site,” she said. “To realize how significant somes of the pieces were — it helps them get so much more out of it. At this age, students learn so much from experiential learning. Getting their hands literally dirty.”