Online classes promise a less expensive way to level the academic playing field, but there’s a cost to virtual instruction, new Northwestern University research suggests.

In a study of high-achieving eighth-graders, the students who took Algebra 1 online performed worse than similar students taking Algebra 1 in a traditional classroom, according to research published in the journal Economics of Education Review.

The students in the virtual classroom also underperformed relative to their peers who waited until ninth grade to take Algebra 1 in a traditional classroom.

“There’s lower academic performance in a virtual classroom,” said study author Jennifer Heissel, a researcher at Northwestern’s School of Education and Social Policy. “Parents should know there’s a cost to going online.”

It’s possible that eighth graders are not developmentally ready to use a self-directed online program, and it may benefit younger students to wait, Heissel said.

The study exploited a 2011 district policy change in North Carolina that allowed advanced eighth-graders to take Algebra 1 online. Prior to the change, none of the middle school students took Algebra 1; instead they waited until ninth grade to take it in a regular classroom.

North Carolina has developed one of the leading virtual education systems in the country, allowing rural middle school students the chance to take high school courses that would be otherwise unavailable. The virtual Algebra 1 middle school program increased equity in access at a lower cost than a traditional classroom, and most advanced students passed the course.

“However, equity in access does not guarantee equity in outcomes,” Heissel wrote in the study. “Policymakers should carefully weigh these tradeoffs.”

What surprised Heissel most was that the effect was seen in students who normally perform above average.

 "Generally, no matter what you throw at high achievers, they end up fine,” Heissel said. “That’s what concerns me: If even the advanced students can’t do well, why would we think it would work well for all?”