The first national analysis of its kind has found that K-12 students enrolled in online public charter schools — where they take all courses online — seriously lag their counterparts in traditional public schools in math and reading achievement. (David Paul Morris/BLOOMBERG)

Students in the nation’s virtual K-12 charter schools — who take all of their classes via computer from home — learn significantly less on average than students at traditional public schools, a new study has found.

The online charter students lost an average of about 72 days of learning in reading and 180 days of learning in math during the course of a 180-day school year, the study found. In other words, when it comes to math, it’s as if the students did not attend school at all.

“There’s still some possibility that there’s positive learning, but it’s so statistically significantly different from the average, it is literally as if the kid did not go to school for an entire year,” said Margaret E. Raymond, project director at the Center for Research on Education Outcomes, or CREDO, at Stanford University.

It was the first national study of its kind to examine the academic impact of online public charter schools, which receive tax dollars but operate privately, often under the leadership of for-profit companies.

The study looked at students attending full-time, publicly funded virtual schools in 17 states and the District of Columbia and annual academic performance between 2008 and 2013. It excluded students who take one or two online courses but spend the bulk of their time in a “brick and mortar school” and those who attend blended learning schools, which offer a mix of traditional and online instruction.

The average online charter student lagged in reading achievement behind their counterparts attending traditional schools in all states except for Wisconsin and Georgia, where their growth was “significantly stronger.”

When it comes to math, students attending online charters did worse in 14 states and performed the same as their counterparts at traditional schools in three states — Illinois, Michigan and Wisconsin.

“It may be good for some students, but the evidence suggests for the majority of online students, the online charters are not serving them very well when it comes to academic growth,” said James L. Woodworth of CREDO, which collaborated on the study with the Center on Reinventing Public Education at the University of Washington and Mathematica Policy Research.

Policymakers need to improve the oversight they are exercising over online public charter schools, said Robin Lake, of the Center for Reinventing Public Education. That’s often complex because online charter school companies are “a significant lobbying force in many states,” she said.

Researchers found that most of the online public charter schools struggle with engaging students and rely a significant amount on parents to help students with their online studies, transferring some of the responsibility that a teacher has in a more traditional school setting to parents. Since students enrolled in an online charter school might live far from the school’s operation center, it is possible that no one in the family would ever meet a teacher or administrator face-to-face.

Nina Rees, president and CEO of the National Alliance for Public Charter Schools, said her group was “disheartened to learn of the large-scale underperformance of full-time virtual charter public schools. While we know that this model works for some students, the CREDO report shows that too many students aren’t succeeding in a full-time online environment.”

Rees said her organization believes that state and local officials who authorize the creation of online charter schools must either “dramatically” improve their oversight, even if it means closing poor performers.

The CREDO study was funded by the Walton Family Foundation, which has given significant financial support to public charter schools.

In a joint statement, Marc Sternberg, K-12 education program director and Marc Holley, the evaluation unit director at the foundation, called on public officials to crack down on low-quality virtual schools.

“Going forward, we will be evaluating these schools with added rigor, and will need to see that providers are addressing the significant issues this study raises before even considering an investment,” they said.

“We urge charter school authorizers and state-level policymakers to carefully review these findings as well and learn from them,” Sternberg and Holley said. “Holding schools accountable for results is vitally important to students. Policymakers cannot ignore students who are lagging a full year behind their peers in math and nearly a half a school year in reading. Policymakers should intervene to ensure that children are well served, and authorizers should not enable such low-quality schools to continue operating unchecked.”