Online credit recovery classes, where students who fail a course on their first attempt retake it online, are booming in Georgia and nationally.

Educators say online credit recovery courses can keep students from dropping out. They can work through the online lessons at their own pace and on their own schedule. And some students say they prefer online courses to traditional classrooms.

But some teachers and students say the largely unregulated courses do more to boost graduation rates than help students learn material they didn’t get the first time around, leaving them with high school diplomas but without the skills they need to succeed in college or at work.

Statewide, about 90 percent of Georgia students who took one of these courses last year in subjects covered by state tests passed the course itself. But an Atlanta Journal-Constitution analysis of results of the state-required tests found only about 10 percent of them were proficient in the subject.

It’s hard to say how many Fulton County students in these classes have actually mastered the material because of an error in how Fulton reported information about online credit recovery courses to the Georgia Department of Education. The district is investigating if the error can be corrected, spokeswoman Susan Hale said.

Across all subjects, Fulton online credit recovery students passed about 80 percent of their classes. That’s close to Cobb County’s rate and significantly higher than Atlanta’s.

Fulton district officials have not spoken with the AJC in response to multiple interview requests.

But district data shows Fulton is the only metro Atlanta school district where enrollment in online credit recovery courses is declining. About 100 fewer students took one of these classes last year than in 2014, district data shows.

Read more: Retaking classes online: ‘Awful if someone really wants to learn’