By Alan Elsner
Columbia, Maryland - Elizabeth and Teddy Dean are learning about the Italian scientist Galileo, so they troop into the kitchen, where their mother Lisa starts by reviewing some facts about the Renaissance.
Elizabeth, 11, and Teddy, eight, have never gone to school. Their teachers are primarily their parents, which places them in what is believed to be one of the fastest growing sectors of the United States education system - the home-school movement.
For their science lesson, Teddy and Elizabeth are joined by three other home-schooled children, who live down the street in their suburb midway between Baltimore and Washington DC.
Before the lesson starts, all five children change into Renaissance costumes - long dresses and bonnets for the girls, tunics and swords for the boys.
"We definitely have a lot more fun than kids who go to school," Elizabeth said.
Nobody is quite sure exactly how many American children are being taught at home. The National Center for Education Statistics (NCES), in a 2003 survey, put the number that year at 1,1 million.
The Home School Legal Defense Association, which represents some 80 000 member families, says the figure now is quite a bit higher - between 1,7 and 2,1 million.
But there is no disagreement about the explosive growth of the movement - 29 percent from 1999 to 2003 according to the NCES study, or 7 to 15 percent a year according to HSLDA.
This growth has spawned an estimated $750 million a year market supplying parents with teaching aids and lesson plans to fit every religious and political philosophy.
Home-schooled children regularly show up in the finals of national spelling competitions, generating publicity for the movement.
Parents cite many reasons for deciding to opt out of formal education and teach their children at home.
In the NCES study, 31 percent said they were concerned about drugs, safety or negative peer pressure in schools; 30 percent wanted to provide religious or moral instruction while 16 percent said they were dissatisfied with academic standards in their local schools.
"I wasn't sold on the idea of institutionalised education. It's a factory approach - one size fits all," said Isabel Lyman, author of The Homeschooling Revolution who taught both of her now-grown sons at home.
"The schools take all the joy out of learning. They don't take account of a particular child's interests, needs and development. The whole system is anti-child," she said.
Different states take widely varying approaches to home schooling. Some, like New York and Pennsylvania, require that the parents submit lesson plans four times a year and regularly test the children.
Others, like Texas, basically leave them alone. So there is little reliable data on how they are doing, said University of Colorado education professor Kevin Welner.
"There are popular myths that home-schooled children are socially inept, cloistered kids and that they are either illiterate or academic wunderkinds. Anecdotes aside, we simply don't have the data to make such generalisations," he said.
"Some children will get top-notch instruction. Others will get poor or minimal instruction. Obviously it will vary by parent," he said.
Even the cliche that the majority of home-schooled children are evangelical Christians is outdated, if it was ever true.
The movement remains overwhelmingly white and middle class but it is growing fast among black and Hispanic families and becoming more politically and religiously diverse as well.
Some parents follow an educational philosophy known as 'unschooling' where the children are encouraged to follow their own interests rather than adhering to a fixed curriculum.
Laura Derrick, president of the National Home Education Network, has followed this philosophy with her 14-year-old son and 12-year-old daughter.
"My son learned to read before he was three and I realised then we were working better than any school programme ever designed," she said. "Children are born wanting to learn."
Lisa Dean, who was a lawyer before she became a mother, said home schooling her children was tremendously rewarding but also very exhausting.
"It's a long day with the kids. I look forward to when my husband comes home," she said.
She also has backup from a local group of 70 home-schooling families who organise group field trips and extracurricular activities. Her children both take lessons in Celtic music on the fiddle, play soccer and basketball and have tried classes in art, hip-hop dancing and kick boxing.
Back in science class, the children were satisfied that heavy and light objects both fall to earth at the same speed, just as Galileo observed, even if neither they nor their mothers seemed to know why. And then it was time for lunch.