CHICAGO (AP) — A sense of order and decorum prevails at Noble Street College Prep as students move quickly through a hallway adorned with banners from dozens of colleges. Everyone wears a school polo shirt neatly tucked into khaki trousers. There’s plenty of chatter but no jostling, no cellphones and no dawdling.

The reason, administrators say, is that students have learned there is a price to pay — literally — for breaking even the smallest rules.

Noble Network of Charter Schools charges students at its 10 Chicago high schools $5 for detentions stemming from infractions that include chewing gum and having untied shoelaces. Last school year it collected almost $190,000 in discipline “fees” from detentions and behavior classes — a policy drawing fire from some parents, advocacy groups and education experts.

Officials at the rapidly expanding network, heralded by Mayor Rahm Emanuel as a model for the city, say the fees offset the cost of running the detention program and help keep small problems from becoming big ones. Critics say Noble is nickel-and-diming its mostly low-income students over insignificant, made-up infractions that force out kids administrators don’t want.

“We think this just goes over the line ... fining someone for having their shoelaces untied (or) a button unbuttoned goes to harassment, not discipline,” said Julie Woestehoff, executive director of the Chicago advocacy group Parents United for Responsible Education, which staged protests last week over the policy after Woestehoff said she was approached by an upset parent

Students at Noble schools receive demerits for various infractions — four for having a cellphone or one for untied shoelaces. Four demerits within a two-week period earn them a detention and $5 fine. Students who get 12 detentions in a year must attend a summer behavior class that costs $140.

Superintendent Michael Milkie said the policy teaches the kids — overwhelmingly poor, minority and often hoping to be the first in their families to attend college — to follow rules and produces in a structured learning environment. He points to the network’s average ACT score of 20.3, which is higher than at the city’s other non-selective public schools, and says more than 90 percent of Noble graduates enroll in college.

While fights can be an almost daily occurrence in some urban high schools, Milkie says there’s only about one a year on each Noble campus.

By “sweating the small stuff ... we don’t have issues with the big stuff,” he said.

Milkie said the fines also help defray the cost of administering after-school detention and the salary of the network’s dean of discipline, which otherwise would divert money intended for education.

But Donna Moore said the district is manufacturing problems that lead to unproductive badgering of students, including her 16-year-old son, who had to repeat ninth grade at Noble’s Gary Comer College Prep after racking up 33 detentions and several suspensions.

“It was nothing egregious, but just that the little things added up: a shirt unbuttoned, shoes not tied, not tracking the teacher with his eyes,” said Moore, adding that her son has an attention disorder. “It’s not normal to treat a young adult as a 2-year-old ... kids internalize that.”

Woestehoff and Moore said some families have removed their children from Noble schools because they couldn’t keep paying the fees, though Moore said her biggest complaint is the infractions. Milkie said Noble sets up payment plans and on rare occasions waives the fees, and students never would be held back a grade solely because they couldn’t pay.

Even so, Matthew Mayer, a professor in the graduate school of education at Rutgers University, said a monetary fine is “highly inappropriate” because it likely has no bearing on students’ academic performance and disproportionately hurts poor families.

“It’s almost medieval in nature. It’s a form a financial torture, for lack of a better term,” Mayer said.