"The National Education Policy Center found about 27 percent of online schools met federal achievement standards in the last school year. That compares to about 51 percent at brick-and-mortar schools.
"The study says the largest growing subgroup of public charter schools is virtual -- or online -- schools.
"Western Michigan University education professor Gary Miron co-authored the study.
"He says there are also questions about the accountability of for-profit charter schools that offer online education.
"'One of the issues that has been coming up is that many of these virtual schools enroll students, then these students don't actively participate,' Miron says. 'However, the school continues to receive money.'"