WINDHAM — Shoppers at supermarkets and big-box stores in town take home at least 9,550 plastic bags per day.

Sierra Yost, an eighth-grader at Windham Middle School, is trying to put a stop to it.

Inspired by a science class project on plastics, Sierra presented a proposal to the Windham Town Council on Tuesday to ban plastic bags and charge 10 cents for non-recyclable paper bags at the checkout counters of stores larger than 2,500 square feet.

“They were really impressed with all the information I found,” said Sierra, who came up with the figure for local plastic bag use by calling Hannaford, Shaw’s, Walmart and Marshalls.

Now town staff is rewriting her proposal into the form of an ordinance for the council to consider at an upcoming meeting.

“There’s a lot of interest in it between the councilors. I don’t think it’s a bad idea,” Councilor Tom Gleason said Friday.

Towns and cities throughout the country — from Westport, Conn. to San Francisco — have imposed bans and fees on non-reusable bags.

The sustainability subcommittee of the Portland City Council considered a similar proposal last year, but decided to put the discussion on hold.

Councilor David Marshall said he expects the committee to take up the topic again this year.

“As far as we know, this would be a first in Maine,” Maine Municipal Association spokesman Eric Conrad said of Sierra’s proposal.

A group of environmental advocates, government officials and businesses launched a statewide campaign in 2009 to reduce the use of plastic and paper checkout bags by 33 percent by 2013.

Abby King, a policy advocate for the Natural Resources Council of Maine, said use of non-reusable bags has decreased since then, but she didn’t know by how much.

Sierra believe efforts to get people to recycle or stop using plastic bags voluntarily haven’t been effective enough.

“We have to go a step farther,” she said.

Although Sierra was assigned a project on the benefits of plastics, she said it was what she learned about the negative impact that struck her most.

She said she learned that plastics break down into smaller pieces that can end up in the ocean and get eaten by animals, and also by humans.

“That was a really scary thought,” Sierra said. So, she decided to take action.

“I would love to say that I had a part in this, but it truly was all initiated and carried out by Sierra,” her science teacher, Sarah Carlson, wrote in an email. Sierra’s mother, Marla Pettinelli-Brown, saidher daughter “took over the dining room table” for the project.

“When she’s passionate about something, she’s passionate about something,” said Pettinelli-Brown, recalling that her daughter read seven Harry Potter books in a month during fourth grade.

Sierra first approached her latest undertaking by calling the larger stores in town and asking them to stop offering plastic bags to customers.

“They all said it was a corporate thing,” she said.

When her calls to the stores’ corporate offices weren’t returned, she started working on her proposal to the town — a course of action that she learned, through her research, had been taken in other parts of the country and the world.

The week before her presentation to the council, she was still collecting information. She put out a survey to Windham Middle School parents asking where they shop and what type of bags they use.

More than half of the 60 people who responded said they use reusable bags — a figure that didn’t match the statistic she got from the local Shaw’s supermarket, which indicated that 85 percent of customers use plastic.

Both were included in a fact sheet she gave to councilors Tuesday during her presentation, which she said “went really well.”

In many ways, Sierra, who turned 14 on Saturday, is like a lot of kids her age. She takes jazz lessons and plays on sports teams. Her favorite color is pink, which is also the color of the elastic on her braces. She saw “The Hunger Games” twice.

In other ways, Sierra, a member of the gifted and talented program, stands apart from her peers.

Kim McBride, her language arts teacher for the past three years, described her as a student “who’s able to express her thoughts in a clear, organized way” — a trait McBride believes helped her in her presentation.

“Sierra’s just particularly thoughtful,” she said. “She’s a student who will definitely make a difference in the world.”