This article focuses on a private corporation, K12 Inc., the largest provider of virtual schooling in the United States with 98 thousand students this year. It also discusses the overall use of virtual schooling  in the United States.
"About 250,000 students are enrolled in full-time public virtual schools in 30 states, according to Susan Patrick of the International Association for K-12 Online Learning, a trade association. Although that’s just a fraction of the country’s 50 million schoolchildren, the numbers are growing fast, Patrick said.......
"K12 sells a variety of ways to learn online, ranging from hybrid schools — in which students meet in a classroom but take courses via computer — to a la carte courses purchased by traditional schools.

"Last year, K12 formed a joint venture with Middlebury College to offer foreign language courses. This year, it bought a stake in a Chinese company that teaches English online.

"But K12’s core business — and the one proving most controversial — is full-time virtual public schools........

"While virtual schools continue to expand, their effectiveness is unclear.

“'We have no real evidence one way or another,' said Tom Loveless, a Brookings Institution scholar who served as a paid consultant to K12 in its early years.

"A 2009 analysis by the U.S. Education Department found that there wasn’t enough research to draw conclusions about how elementary and secondary students fare in full-time virtual schools compared with classrooms.

"On measures widely used to judge all public schools, such as state test scores and graduation rates, virtual schools — often run as charter schools — tend to perform worse than their brick-and-mortar counterparts.

"At the Colorado Virtual Academy, which is managed by K12 and has more than 5,000 students, the on-time graduation rate was 12 percent in 2010, compared with 72 percent statewide.

"That same year, K12’s Ohio Virtual Academy — whose enrollment tops 9,000 — had a 30 percent on-time graduation rate, compared with a state average of 78 percent."

By Lyndsey Layton and Emma Brown, The Washington Post, Published: November 26, 2011