Boredom is the biggest cause of pupils losing interest in school, says the School Standards Minister David Miliband.
"A significant minority of young people, especially boys, get turned off in secondary school soon after they arrive," said Mr Miliband.
"If I had to pick out a fundamental reason why this minority get turned off, I would have no hesitation: boredom."
Boredom is the bane of education ... the recruiting sergeant for disaffection, truancy and bad behaviour
David Miliband, School Standards Minister
Speaking at a conference in London about education links with business, the minister said that boredom was at the root of many discipline problems.
"Boredom is the bane of education. Boredom is the recruiting sergeant for disaffection, truancy and bad behaviour.
"Boredom is the gateway to dropping out. It is the proof that adults just don't understand and have nothing to offer."
And Mr Miliband warned that boredom could put children at danger
"Boredom at school is what makes parents worry that their kids will turn to excitement beyond safe boundaries. Bored children are a danger to themselves and a disruption of the education of other children."
And Mr Miliband said that the government's proposed reforms for secondary school would help to tackle this problem of disaffection.
This would include introducing a greater role for vocational training in schools.
There would also be an extended role for information technology.
He also called for schools to make better use of their facilities, with longer opening hours and wider access during the holidays.
And he called for the style and pace of teaching to reflect the needs of young people.