For the last six weeks, 23 eighth-graders at Broadmoor Middle have taken a break from worksheets and textbooks to tackle a simple but vexing problem: how to prevent rain from mixing with trash and chemicals on the ground and polluting nearby streams and lakes.

Stormwater runoff is a major source of environmental pollution.

The students, though, weren’t laboring alone. They had a handful of mentors, professionals with careers in science, technology, engineering and math, or STEM, fields.

Team Cisco, named after Cisco Systems, as the mentors call themselves, is one of 10 such teams working with teenagers and preteens at six middle schools in Baton Rouge. They are part of a new program called STEMup Baton Rouge.

Friday was the day of truth for the Broadmoor Middle eighth-graders and their efforts to stop stormwater runoff.

They’d broken into four groups, and each had labored to build small, rudimentary model cities. Using everyday materials, each group came up with slightly different strategies for limiting stormwater runoff.

Most employed variations on green roofs, with materials such as sponges and moss used as substitutes, but some models used different kinds of ground cover to arrest the flow of water.

“We put some soil and moss and rocks in there,” explained Anthony Alvarez, who presented on behalf of Station 3, one of the four teams. “And we put these walls of aluminum around it, so even if it was filled (with water), it wouldn’t go over the walls.”

In the parking lot, in addition to cotton balls, felt and bits of protective screen, the team installed another obstacle.

“We put a speed bump here so that the cars would go through, but the water wouldn’t,” Alvarez said.

Finally, it was time to put the model to the test.

One student poured glitter, representing trash, another poured Palmolive soap, representing chemicals, and a third sprayed the model city repeatedly with water from a spray bottle, akin to a light rain. The city rested at a slight tilt as all three elements mixed. If the mixed water spilled off the edge, the model failed.

It didn’t. Station 3 retained the water. Three of the four teams, in fact, were a success.

Afterward, several students said they enjoyed learning through experiments.

“It’s better to learn this way, because we could actually experiment and do it physically rather than watching it on YouTube,” Tiphanie Nunnery said.

The team said the adults were a big help in steering them straight.

Reatha Wright, a retiree from a state agency where she worked as a project manager in telecommunications, said she relished showing the students what math and science are really like.

“It was so good to interact with the students and watch them as they brainstormed their way through the process,” she said.

The experiment, although small in scope, was similar to a real-world project, Wright said, because it had a budget and involved lengthy planning and design.

Sadereka Evans, environmental science teacher, said each model city started off an empty rectangle. Filling them was the students’ biggest physical but also conceptual challenge, she said.

“Here is a naked platform and I want you to build something,” Evans said. “In education, a lot of things have been scripted out for them over the years.”

Student interest grew as the mentors began visiting her classroom, Evans said. They brought with them an authority on the subject that she, a nonengineer, could not match. Evans said she got to be a student herself a bit, working with some teams and listening to the mentors.

“This should be norm where students build, build, build. They should create; they should investigate; they should explore and experiment to see how science works,” Evans said. “A lot of science I’ve seen through the years is, ‘The book says, the book says, the book says.’ ”

STEMup Baton Rouge made it easier for Evans by providing the instructional materials for free and taking care of the planning for each activity.

The mentoring program, which launched in the fall, is a joint effort of the Foundation for the East Baton Rouge School System and the Capital Area United Way, and is being underwritten by a grant from Capital One.

Kim Fossey, who works with the foundation, said she hopes to have enough money to offer mentoring at all 15 middle schools in the parish school system next year.

Evans’ students have an idea for the next project: fix up Broadmoor Middle School itself.

“You know how the school has a flat roof?” Nunnery asked. “It would be cool if we could put a green roof on top of our roof.”

“It would also slow down air pollution,” added John Brandon.

Follow Charles Lussier on Twitter, @Charles_Lussier.