Nearly 30 parents are defying education chiefs by trying to set up classes in Wycliffe community college - one of the secondary schools closed in a radical shake-up to make way for the new, 2,000-pupil New College.
The protesting parents say that Wycliffe should never have been closed, and they have taken over a community room on the premises where they are pleading for worksheets and teachers.
The protest has already had some success, with two Leicester University lecturers and one unemployed teacher offering their services free of charge.
Leicester City Council's acting education director, Tony Webster, has sent a letter to the rebel parents telling them to quit their protest.
"Every parent has a duty to ensure that their child receives efficient, full-time education suitable to their age, ability and aptitude through regular attendance at school," he wrote.
"Failure to ensure such attendance is an offence and may lead to prosecution."
The parents, however, are taking legal advice, and say they will carry on with their action.
Action group spokeswoman, Tracy Woolman, said: "We are not refusing to send our children to school. They are attending Wycliffe. There are several reasons why we do not want them to go to New College, ranging from transport difficulties to the sheer size of the place, and the mix of pupils."
Education welfare officers and Judith Mullen, head of the new superschool and the president of the Secondary Heads Association, have visited Wycliffe to talk to the protesting parents, but to no effect.
Mrs Mullen said: "As far as I'm aware these children are not getting a proper education and the only reason we are letting them use the building there at all is because it is a place of safety."
Meanwhile, parents in Barnet, north-west London, are threatening to take the borough to the Equal Opportunities Commission for failing to provide enough places in all-girl schools.
They are refusing to send their daughters to Whitefields School in Cricklewood, which they say is not up to the required standard, and insist they should be admitted to the nearby single-sex Queen Elizabeth's School.
Their protest comes after the girls were denied places at Queen Elizabeth's, which is over-subscribed. Barnet Council, one of the few London boroughs providing single-sex schools, insists it is not guilty of sex discrimination.
The council said the parents were entitled to apply to neighbouring boroughs for places at single-sex schools. The parents have made private arrangements for their children's education while the dispute continues.