England's schoolchildren should have shorter holidays and spend more time in the classroom, Michael Gove said on Thursday.
The Education Secretary called for longer school days and term times, warning that the current system is out of date and fit for the agricultural economy of the 19th century.
Gove: 'some of the best schools in the country are moving to a longer school day'
In a speech on Thursday, Gove said that pupils are at a "significant handicap" compared to youngsters in East Asian nations who benefit from extra tuition and support from teachers.
"We've noticed in Hong Kong and Singapore and other East Asian nations that expectations of mathematical knowledge or of scientific knowledge at every stage are more demanding than in this country," he told a Spectator conference in central London.
"In order to reach those levels of achievement a higher level of effort is expected on behalf of students, parents and teachers.
"School days are longer, school holidays are shorter. The expectation is that to succeed, hard work is at the heart of everything."
Gove added: "If we look at the length of the school day in England, the length of the summer holiday and we compare it to the extra tuition and support children are receiving elsewhere then we are fighting, or running, in this global race in a way which ensures we already start with a significant handicap."
He later said that he wanted to see schools introduce a longer day for pupils, suggesting that some are already "recognising that we need to change the structure of the school term and in particular that it is poorer children that lose out from longer holidays."
"It is also the case that some of the best schools in the country are moving to a longer school day as well."
Gove said that the Government was making changes to teachers' pay, terms and conditions which would mean they could be paid more for taking on extra duties and allow headteachers to organise their staff "in a way to get more out of young people".
"It may be that there are one or two legislative or bureaucratic obstacles that prevent all schools from moving in this direction but I think it's consistent with the pressures of a modern society," he said.
He insisted that changes to term times and the school day would be "family friendly".
He added: "I think it's the case that the structure of the school term and the school day were designed at a time when we had an agricultural economy.
"Half term in October, when I was at school in Aberdeen it was called 'tattie holiday' because it was the period when children went into the fields to pick potatoes.
"It was also fixed on a world where a majority of mums stayed home. That world no longer exists and we can't afford to have an education system that essentially its hours were set in the 19th century."
Under the current system, the school year is 190 days long. Pupils get around six weeks off in summer, two weeks at Christmas and Easter as well as three half-term breaks lasting a week each.
School days usually run from around 9am to 3pm, or 3.30pm.
The Department for Education said a number of academies - which are free from local authority control - are altering the length of the school day.
Schools in the Ark Academy chain have days which run between 8.30am and 4.30pm four days a week, with pupils finishing at 3pm on Friday, while the Haberdashers' Federation of academies have changed their term times to start the year early, the DfE said.
It added that Milton Keynes Academy has six terms of six weeks, with a shorter summer holiday and two-week holiday in October and the David Young Academy in Leeds has a seven-term school year which starts in June.
Brian Lightman, general secretary of the Association of School and College Leaders (ASCL), said: "Some schools are introducing innovative changes to the school day and term and it will be interesting to see what effect these have in the longer term on achievement.
"But changes should be based on sound, researched evidence, not on anecdotes from other countries with vastly different cultures and attitudes to education. The quality of the learning happening in classrooms when children are in school is more important than the number of hours they spend there."
Christine Blower, general secretary of the National Union of Teachers, said: "Teachers and pupils already spend longer hours in the classroom than most countries and also have some of the shortest summer holidays.
"Independent schools in England and Wales, which often break for two weeks more during the summer and have longer holidays at other times of the year than their state counterparts, do not apparently feel the need to change and are apparently not suffering from their reduced hours.
"Yet again we see the Education Secretary making policy up on the hoof with no real evidence for either the necessity for change or the benefit it brings".
At their Easter conference this year the NUT called for new limits on working hours amid concerns that school staff are facing "totally unsustainable'' workloads.
Delegates at the conference backed a decision by the NUT's executive to draw up a draft contract setting out a 35-hour working week for teachers.
This would include 20 hours of "pupil contact time'' - the equivalent to four hours a day in the classroom - as well as 10 hours for lesson planning, preparation and assessment, and five hours for "non-contact duties'' such as staff meetings, parents' evenings and logging pupils' results.
The Prime Minister's official spokesman said David Cameron backed the need for reform.
"He absolutely agrees with the central point that the Secretary of State for Education was making which is that we have to reform a whole series of parts of our education system to reflect the very modern global race that the UK is in."
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