It is estimated that 850,000 children in this country are home-schooled -- the overwhelming majority by parents who have only the best interests of their children at heart.
But homeschooling is largely unregulated. A CBS News investigation reports how some children have suffered abuse -- and much worse -- while no one was watching.
Neil and Christy Edgar will be sentenced next month in Kansas for abusing and murdering their 9-year-old son. He suffocated after his head was wrapped in duct tape as a punishment for taking food without permission.
It's a shocking case, but as CBS News Correspondent Vince Gonzales reports, not an isolated one. A CBS News investigation found dozens of cases of parents convicted or accused of murder or child abuse who were teaching their children at home, out of the public eye.
"A lot of reports for suspected abuse or neglect are made by the schools when they observe children coming in that may be bruised or not well fed," says Marcia Herman-Giddens, of the North Carolina Child Advocacy Institute.
In Iowa, a father is serving life, and a mother goes on trial later this month, for killing their 10-year-old adopted son and burying him at their house. Because they were home schooling, no one noticed he was missing for more than a year.
There are two notorious Texas cases.
Andrea Yates gained national attention when she drowned her five children in a bathtub. Deanna Laney, told investigators she beat her three sons with rocks, killing two of them. Both mothers taught their children at home.
"The genuine home schoolers are doing a great job with their children, but there is a subgroup of people that are keeping them in isolation, keeping them from public view because the children often do have visible injuries," says Herman-Giddens.
Even a very public home school success story can hide a private dark side. Marjorie Lavery says her father beat her before the National Spelling Bee then threatened to kill her after she came in second. He pleaded guilty to child endangerment after she testified about years of cruelty.
Hal Young and other home school advocates vigorously defend the right to teach their children at home without government intrusion.
"The cases that you've mentioned are very, very rare - extremely rare," says Young.
"There's not a pattern there, there's not a trend," says Young. "It's not something you can point your finger at and say there's this vast undercurrent, because there's not."
But it's hard to know how widespread abuse might be because the government doesn't keep track. It doesn't even know how many children are taught at home in this country.
In eight states, parents don't have to tell anyone they're home schooling. Unlike teachers, in 38 states and the District of Columbia, parents need virtually no qualifications to home school. Not one state requires criminal background checks to see if parents have abuse convictions.
The Edgars now face life in prison. The dilemma raised by their case and others: how to protect parents' rights to raise their children and still protect children from parents who abuse them.