Bullying is often the spark, though it can be religion. For Ben Morris and his father, Tim, a row over geography homework on a miserable Sunday afternoon seemed to have been the great catalyst, while for Mrs Wendy Plested it all came down to her eldest daughter's slow descent into agoraphobia.

The reasons why parents choose to take their children out of school, or decide never to send them in the first place, are indeed varied, writes Reg Little. But it now seems that, in Oxfordshire, more mothers and fathers are becoming DIY teachers in the hope of offering their offspring a better education.

As most of Oxfordshire's children prepare to return to school on Tuesday after the Easter break, a much envied group will be settling down to their books, television sets and computer screens in the comfort of their own homes. At least a hundred parents in the county have chosen to turn their backs on the education system, effectively freeing their children from the national curriculum and the stress of SATS examinations. For some parents, it represents the ultimate gamble, with few things more crucial than their children's education, while for others it means sacrificing their own careers for the privilege of teaching their youngsters exactly as they see fit.

No teaching qualification is apparently necessary, no timetable has to be drawn up by the Education Secretary, Mr David Blunkett, or even officers of the local education authority. Astonishingly, it is simply up to each parent and child to work on just what they want to, when they want to.

Mrs Plested, who lives in a housing association home in Webbs Close, Wolvercote, is one of the county's most experienced home teachers, having been teacher to five of her own children. She is also the Oxford co-ordinator of Education Otherwise, the self-help organisation created to offer support and advice to parents practising or considering education at home. In her case, she says her hand was forced by the years of bullying endured by her eldest child, Rebecca, at Lark Rise First School, Oxford, and later at Isis Middle School. "Rebecca would come home with her back bruised from being stabbed with pencils. She would have her work torn up by other children and come home with her lip split.

"I think it happened simply because she was bright and asked a lot of questions. She was very young when it began but it always appears that when a child has been bullied early in their school life, they seem to walk around with "victim" on their forehead. They just seem to go on attracting bullies.

"Rebecca ended up not just being school-phobic but agoraphobic. She became frightened of going out of the house."

It is alarming to hear from Mrs Plested that bullying is, in fact, by far the most common reason why parents take their children out of school. More than anything, it is an act of rescue. However, she now says that the bullies unwittingly opened the door to a new world for her. "It is a big commitment," said Mrs Plested, 40, whose husband works for a Amey Rail inspection team. "It is not a decision that anyone should take lightly. It should not simply be seen as an instant cure for problems being experienced at school.

"At the beginning, a parent may well have doubts about their own abilities. You end up comparing yourself with the school. But now I feel that my children receive a wider education through not being bound by the curriculum.

"They are able to follow their interests as deeply as they want to." It is a statement enough to make parents of a football-mad or Pokeman-obsessed child shudder.

But Mrs Plested remains relaxed about letting her children set the agenda to a large extent.

"I took my son David out of school because he found it boring the maths was simply not challenging enough."

She points to the fact that he now goes to a music teacher and a Latin tutor, who happens to be the sister of another self-taught teacher-mother. Where possible, she says, parents involved in Education Otherwise do try to share around specialist skills, with the self-help ethos to the fore. As well as David, 12, she also has Jack, eight, and Scarlett, five, to teach. Rebecca now works in Boots, Summertown, north Oxford, while eldest son, Gareth works in the Co-op in Marston, Oxford. "It does change the fabric of family life," she said. "I spend three and a half hours working with them every morning, with the children working by themselves in the afternoon. I choose to plan the work very carefully but we also enjoy many museum visits and things like archaeological digs and theatre trips. Wherever we go, they treat us like a school."

The teaching programme devised by Dr Tim Morris for his 11-year-old son, Ben, is far more computer and Internet-based. Dr Morris, an editor at Oxford University's Refugee Studies Centre, and his wife, Ianthe, the Oxfordshire Children's Rights Commissioner, are even able to continue in full-time employment, with Dr Morris reckoning to spend only about 15 minutes a day engaged in teaching.

Every day from his office he sets Ben work sent by e-mail, with his son also supplied with educational computer software and videos of BBC Learning Zone programmes. Once a week, Ben attends a maths tutorial and his father is now confident that he will be able to sit a GCSE in maths next year. It all represents something of a remarkable turnabout since Ben was taken out of St Frideswide Middle School a year ago.

"I didn't like school," said Ben, of Linkside Avenue, in north Oxford. " I was teased a lot. Then there was the journey to and from school and I was often bored when I got there. To be honest, I didn't get a lot of work done in class. It was a big class and there were a lot of distractions, with the teachers often getting very cross. I really didn't have that many friends. But then I am not very interested in football and television."

His father, who edits the Forced Migration Review, was concerned about the boy's apparent drop in confidence. "I became aware that he was not happy and not stimulated. I felt his talents were not being brought out at school and that he was not getting much work done. The school system managed to persuade him that he was bad at maths, suppressing his natural enthusiasm for the subject. "Homework was simply awful. I remember having a fight about one piece of homework one Sunday afternoon and deciding that it was just silly. I think that since Ben has left he has become much more focused. Now he can take his GCSE and A-levels at his own pace. He has a structured and varied day. He is learning Arabic and studying comparative religion. I actually believe in state education and did not want to send him to a public school."

Ben talks with a remarkable maturity for his age, yet is not his father worried about robbing his son of school friendships and learning to cope with the rough and tumble of the playground?

"He keeps in touch with some friends from the school," said Dr Morris. But soon father and son are locked in a discussion about institutions where groups of people are thrown together with people of similar age.

Education Otherwise turns the social issue on its head by arguing that research shows home-educated children have greater skills and maturity. Freed from peer pressures, the group says the home-schoolers are able to enjoy the company of both older and younger children and mix more easily with adults and children of the opposite sex. It is an argument that fails to impress Mr John Mitchell, the assistant chief education officer at Oxfordshire County Council. "We discourage parents from going down that road. It is hard to provide the opportunities available in school in terms of social interaction and breadth of learning. But we do not deny parents the right to teach their own children.

"When parents are doing it for the right reason and have the necessary skills, it may work. Problems occur when, for one reason or another, parents have become disenchanted with the mainstream educational system and choose to do it without having the skills themselves.

"Sometimes it is a protest vote and not in the best interests of the children."

While some parents may act through fear that their children are being held back by school, others leave the system because of dread that their children are being left behind.

For David and Karen Buttle, of Upthorpe Drive, Wantage, their religious faith has played its full part. For their curriculum, they have chosen to use material from the American-based Mennonite Church, which practises pacifism and simple living. The couple have even created their own website which seems to celebrate their Christianity every bit as much as their home-school for their children, Samuel, Abby and Benjamin.

But the site is unlikely to attract recruits among many of the exhausted mothers and fathers indulging in a very different celebration this week the end of the school Easter holiday.