Even as they surge in popularity, online schools in Minnesota are troubled by high dropout rates, poor math scores and inadequate state oversight.

That's the conclusion of a state audit released on Monday that shows how the virtual schools, whose full-time enrollment has tripled in recent years, are faring.

It's unclear why many online students are falling short academically, said Legislative Auditor James Nobles, adding, "We need to find out, is there anything more we can do for these students?"

During the 2009-10 school year, Minnesota's full-time online students finished only 63 percent of the courses they started. Just 16 percent of those in high school were proficient on state math tests, compared with 41 percent in the same grades at schools throughout Minnesota. And fully one-quarter of the 12th-graders dropped out by the end of the school year, vastly more than the 3 percent of all students who did so statewide.

Advocates of online learning point out that many students are already behind academically when they enroll. "The majority of the students that come to us were struggling in their previous school, and they've come to us as an alternative," said John Huber, head of Insight School of Minnesota, an online high school guided by the Brooklyn Center School District.

State guidance of online schools is also a problem, the audit concluded. The Department of Education, short-handed, has done little to oversee online schools or clear a longstanding backlog of applications to start new programs, the report found.

The report, requested by legislators, comes as the popularity of online learning is growing. Roughly 12,000 K-12 students -- about 1.5 percent of Minnesota's student body -- took courses from state-approved online schools last year. The number of part-time students in online schools has nearly doubled in the past four years, and the number of full-time students has more than tripled.

State leaders want to make sure education evolves with technology, said Rep. Mike Beard, R-Shakopee, who chairs the legislative audit commission. "What we're really concerned about is, how do we foster innovation, but do it in a way that maintains quality?" he said.

Some legislators are also watching closely the high-profile battle between the state and a pioneering online school, BlueSky. The school is fighting state officials, who have reported violations of state graduation requirements at the school and moved to shut it down.

Minnesota has 24 public K-12 online schools approved by the Education Department. Some are charter schools, while others are run by one or more traditional school districts. Online schools have drawn students with a variety of special needs, including teen moms, elite athletes and victims of bullying.

Some students thrive. Luke Schneider, 17, chose online schooling partly because it gave him more flexibility to help care for his sister, who is autistic and was missing a lot of school around the time that he started high school.

Schneider, of Brooklyn Park, switched to Insight School. Once he started, "I really enjoyed it," said Schneider, who stuck with Insight even after his sister stopped needing as much help.

In online classes, "you get to move at your own pace, whether that's ahead or a little behind," said Schneider, who now takes a mix of online and community college classes.

For many other students, the benefits of online learning include access to classes such as anthropology or AP calculus that their traditional schools don't have the resources to offer, the auditor's report said.

But state leadership leaves much to be desired.

One problem: While public online schools must get state approval, the Education Department has been slow to process applications for new programs.

The Legislature should set specific time frames for state officials to process applications, the report said. It also recommended that the department redesign its approval process, paying more attention to how schools perform.

The department should also assign more staff to work on issues related to online learning, the report said, suggesting that reducing oversight of programs that only take part-time students could help with the state's staffing problems.

Those recommendations drew sharp criticism from Education Commissioner Brenda Cassellius, who opposed many of them in a letter to Nobles. Mandatory timelines, for example, would place "a higher premium on mere approval of online schools over the assurance that students will be well-served by that school," she said.

Sarah Lemagie • 952-882-9016