The plastic sandwich container that second-grader Sophia Todaro pulled out during her lunch period held an unappetizing artifact — a tiny, dead scorpion that her cousin found in the Arizona desert.

“The smaller the scorpion, the more poisonous it is,” she explained to third-graders Mary Khalil and Audrey Wilson.

After asking a series of follow-up questions from an iPad spreadsheet and examining her poster, the third-graders gave Todaro 36 points, even though she decided the scorpion was too precious to part with. ­Todaro redeemed her points for an agate.

It’s all in a day’s work for students at Garlough Environmental Magnet School’s Trading Post, where they are encouraged to bring in natural objects to “trade” for other items, while also presenting independent research on their finds.

Open every morning and lunch period, the trading post is staffed by third-grade curators in Jennifer Parker’s “Whoodinis” gifted and talented program.

After earning points for what they’ve brought in, kids can trade their points for another item in the glass cases in the hallway outside the office. Student-produced posters and reports from previous trades also line the space.

“It is a source of huge pride for them,” said Parker of the third-graders. “It’s all student-centered. I’m just their facilitator and mentor.”

The trading post began last November, but is modeled after the Science Museum of Minnesota’s Collectors’ Corner, which has been around for years.

“We went there when my kids were little and I always thought, ‘Oh my gosh, this would be great to have in a school,’ ” Parker said.

The project started slowly so kids could ease into things. The Science Museum and Parker each donated some items, and Parker bought two glass cases with grant money she’d received.

Now, dozens of items — from coral to sand to pieces of bone — are on display. In addition to engaging with the natural world, students are learning about economic concepts and how to run a business, Parker said.

Early on, students priced items too high and found no one had enough points to buy them, she said, so they lowered the prices, learning about supply and demand.

“It also gets kids writing and researching outside of school,” Parker said. “You can’t just bring something in without spending time researching it. The research is what matters.”

The nine third-graders — marked by their tan vests — were chosen as curators because they could stay with the project for a couple more years, training in kids next year. They give up their lunch and recess time or voluntarily come in before school to staff the post.

“It’s kind of like being a teacher,” said Khalil. “Depending on what they know, they can get more points — and you can give feedback.”

Parker, who has a zoology degree, also serves as the school’s magnet coordinator and teaches a class that uses technology to instruct kids about different natural environments and how people interact with nature in each place.

Fourth-grader Noelle Wang stopped by to show the curators a piece of bark she’d found while walking with her mom and sister. She identified it and received 21 points for her report on River Birch bark.

Wang called the post interesting, adding, “You can trade things you find for something else that you want.”

The school partners with Dodge Nature Center and is adjacent to a park, so all students can find something to trade if they look, Parker said.

Principal Sue Powell said she thought the trading post was a good idea because she likes trying innovative things. And the project plays into kids’ “intrinsic curiosity about bugs and pretty much anything to do with nature,” she said.

Next year, Parker will continue the project, possibly buying a taller case and adding lighting to make the Trading Post more like a museum experience, she said.

“The best projects are when they don’t even realize the academic value of what they’re doing. It’s just fun,” Parker said.