MIAMI — After his father was diagnosed with cancer, a 15-year-old Champagne, Ill., teen started skipping school, erupting in angry outbursts, yelling at teachers and punching holes in walls or retreating to his room paralyzed by an overwhelming sadness.

When the teen’s assistant principal approached him a few months ago about seeking help for mental illness, the student initially declined, saying he didn’t need it. However, eventually he did seek treatment. Diagnosed with major depressive disorder, he joined group therapy sessions at his school.

As stories about increasing school violence dominate headlines, experts say many teens are struggling with untreated mental illness. Yet, school officials around the country are themselves grappling with the best way to offer mental health services in a patchwork, underfunded system.

Although the 15-year-old Illinois student was not diagnosed through a school program, in his school-based group therapy he’s learning practical tips to identify his triggers and calm them before emotions spin out of control.

Federal health officials recommended universal mental health screenings for students nearly a decade ago, but it’s still not required. An AP review of policies around the nation shows screenings vary widely not only from state to state, but within each school district. There’s no consistency on whether the schools screen, what age they screen and what they screen for.

The federal government does not keep track of school mental health screening, so it’s all but impossible to say how many schools do or don’t offer it.