The No Child Left Behind act is a bonanza for private tutoring firms, including Sylvan Learning.

Under the act’s provisions, students enrolled in schools judged to be failing are entitled to free tutoring, paid for by taxpayers. The costs total $2.5 billion annually, according to U.S. News and World Report.

Tutoring companies contract with individual states and school districts. Sylvan provides such tutoring at about half of its 1,200 U.S. locations, according to Tabatha Sweeney-Gehrt, Sylvan’s director of new business development. At some centers, she says, business has doubled because of the service.