AUBURN — The sign outside the Sherwood Heights Elementary School classroom reads: “Green Police Headquarters.”

Wearing the green vest and badge is a sought-after job for the third-graders in William Murray’s classroom, where all of the students are sworn in.

They’re dispatched to roam the halls, escorting younger students as they take paper and cardboard to be dumped and recycled.

Their vigilance hasn’t gone unnoticed.

Murray’s class was honored Wednesday by Kids Consortium and Poland Spring Bottling Co. for completing a two-year “green schools” service project.

The third-graders lead the school in recycling, composting, energy conservation and gardening, learning lessons along the way.

Using a Kids Consortium two-year, $1,000 grant, Murray’s students have been on field trips to ecomaine in Portland to see how paper, bottles, cans and plastic are sorted in single-stream recycling.

They use fruit and vegetable waste to make compost for their school garden. They grow sunflowers for teachers, tomatoes and string beans for the school cafeteria.

They organize biweekly paper collections.

They’ve learned about using less energy, like turning off lights when not needed.

Murray teaches them how to reuse things that would end up in landfills.

Take the Styrofoam lunch trays students are given every early-release Wednesday. Styrofoam is a big environmental no-no, because it doesn’t break down when discarded, Murray said.

The students collect hundreds of trays, “break them into little pieces, and put them in the bean bags around the school,” said third-grader Cole Sirois, 8.

That keeps the trays from going to the landfills and makes their bean bags comfy.

Other things in Murray’s classroom have been rescued from landfills. Student mail boxes are made from blue plastic jugs that used to hold coffee. Chairs and tables have been repaired and painted.

An avid gardener and longtime recycler, the teacher said he applied for the grant because he was looking for something to engage his students. His environmental lessons, like composting, do the job.

Students typically collect 15 to 20 pounds a day from classroom snacks of fruits and vegetables. That waste goes in a composting bin.

“We quantify what we compost,” Murray said. “We weigh it every day, then collect the data.” Students chart, graph and analyze the numbers.

“Instead of taking data that doesn’t mean anything out of a book, we have real-life data that they own,” Murray said. “They collect it. It helps engage them.”

Even though third-graders are young, Murray wants to steer them in environmental ways, and toward jobs of the future. Colleges are just beginning to graduate people to work in alternate energy such as wind and tidal power, he said.

Parents have told him students are taking in the lessons.

“They try to get their parents to recycle,” he said. Some of his students tell him:  “’My mom just throws my corrected papers in the trash. She doesn’t recycle.’ They rat on their parents, and each other.”

If a student puts plastic in the trash or the wrong place, Murray is informed.

Alexis Waisanen, 9, said she coaches her mother “to not throw away plastic bags.”

Dawson Leslie, 9, said he too encourages his parents to recycle. “I have my own little compost pit in the woods with a little fence. I made it.”

Composting food waste is better than throwing it out, he said. “My mom and dad like to garden, so why not? It helps plants.”

bwashuk@sunjournal.com