TRACY -- When it was time for David and Katie Estill to enroll their children in school, they had concerns about the influence of public school on their children, including what they would be taught.

Their solution was not to send them to school at all.

"We'd like to be able to control influences that come into our children's lives," said Estill, of Tracy.

"We wanted to teach them creation. It's not that we don't want them to learn evolution, but we want to present both."

The Estills are among a growing number of parents turning to homeschooling.

The total number of children in homeschools in the state is unknown, because neither the state nor the county counts them.

But as an indicator, the number of children in independent study programs, which include many homeschooled children, increased by 35 percent statewide between the 1999-2000 and 2002-03 school years, according to the state Department of Education. The numbers in San Joaquin County increased 22 percent over the same period.

Teaching a child at home and having more control over what the child learns has strong appeal for many parents frustrated by their current public or private school.

But California law says a child can be taught at home only by a tutor who has a certificate in the subject they are teaching. Otherwise, the child must be enrolled in a public or private school.

Although the boundaries are stricter than other states, parents still can homeschool within them, said Debbie Schwarver, legislative chair of HomeSchool Association of California, an advocacy and support group for parents who homeschool.

Parents who want to stay within the public-school system can contact their county office of education, school district or charter school to ask about available programs, she said.

What's most commonly offered is what's called independent study or home study. Trained teachers create the lessons and provide the course material for students who then work from home.

Locally, Venture Academy, a K-12 school chartered by the San Joaquin County Office of Education, does this for homeschooled children. The academy has four locations, two in Stockton, one in Lodi and one at Durham Ferry Ranch near Manteca. ::: Advertisement :::

Students enrolled in the academy are assigned a teacher who develops individualized academic plans for them. The students complete their studies at home. The lessons are based on the state educational standards and students use similar textbooks as their peers in classrooms. Parents can call credentialed teachers for more help if they need it, and the academy offers math and language-arts classes, along with a number of electives, on the campuses.

New Jerusalem Charter School in Tracy also offers a program for parents who homeschool. Parents can take classes to learn how to be better teachers, borrow books and consult with teachers at the school.

A number of county school districts offer independent-study programs but not all are tailored for homeschools.

Lodi Unified has a number of schools that offer independent study for homeschooled students. But the Tracy, Stockton and Lincoln unified school districts do not.

Parents who want more independence also can register as their own private school. That's not as difficult as it might sound, Schwarver said.

"I could set up a private school in my home tomorrow," Schwarver said. "I could have two students, and that would be perfectly legal."

Parents must fill out a form from the state department of education saying that they are starting a private school. The parent starting a private school is required to keep attendance, immunization and class records.

And parents must teach the basics, including science, math, literature, music and art. But they can decide how and through what materials the subjects are taught, she said.

The association said the state doesn't have the right to inspect or review teacher qualifications, student work or curriculum at a private school.

While homeschooling has grown in popularity, some questions about its efficacy have been raised. The most common is socialization.

Parents who homeschool should find opportunities for their children to interact with other children, said Irene Elliot, a board member of the California Association of School Psychologists.

"Play is really child's work," she said. "Children learn cooperation, getting along, problem solving and negotiation."

Some homeschooled children also may have time-management problems if they re-enter public school in their middle school or high school years.

"They are just overwhelmed with the amount of assignments, the deadlines, the expectations," she said.

The National Education Association has sought to create greater regulation of homeschooling to make sure children are meeting state requirements.

Estill said her children have thrived with the added attention they get in a homeschooling environment.

"We felt we can offer them a better education, because it's one on one," she said.