Why do Finnish pupils succeed with less homework?
How do Finnish youngsters spend less time in school, get less homework and still come out with some of the best results in the world?
The question gets to the heart of a lot of parental angst about hard work and too much pressure on children in school.
Parents facing all those kitchen table arguments over homework might wonder about its value if the Finns are getting on just fine without burning the midnight oil.
As the OECD think tank says: "One of the most striking facts about Finnish schools is that their students have fewer hours of instruction than students in any other OECD country."
Long summer holidays
It also touches on another tension between schools and families - the increased cost of summer holidays.
While children in England and Wales are still toiling away in school into the middle of July, the Finns have already been on holiday for six weeks, in a summer break that lasts 10 to 11 weeks.
And completing this picture of less is more, Finnish children do not in theory have to start school until they are seven - although most will have been in classes from an earlier age.
But when it comes to the international Pisa tests, Finland is in sixth place and the UK is 23rd in reading; and Finland is 12th and the UK is 26th in maths.
Another set of OECD global rankings last year put Finland in sixth place for maths and science.
So what's going on? How do the Finns seem to start later, have fewer lessons and then finish ahead?
Finland, as part of its centenary commemorations next year, has a project to share what works in its schools with other countries.
Saku Tuominen, director of this HundrEd project, says parents in Finland don't really want longer hours in school.
He says there is a "holistic" approach to education, with parents wanting a family-friendly approach.
Why Sean wrote this article:
We asked readers to send BBC Education correspondent Sean Coughlan their questions on schools.
Sean chose four questions, and we asked you to select your favourite, which came from Lukas Milancius, a 16-year-old student.
Lukas asked: "How come Finland has shorter days and no homework for students and yet is achieving more?"
Lukas explained to us the thinking behind his question:
"I want to know why other countries are not adopting this education system. I find myself to be in a difficult situation where I am obliged to do a lot of homework and attend long school days which leaves me with hardly any time for me to do other activities."
Respect for teachers
There is little homework, compared with UK schools, and there is no culture of extra private tuition.
A key concept in the Finnish school system, says Mr Tuominen, is "trust".
Parents trust schools to make the right decisions and to deliver a good education within the school day - and schools put trust in the quality of their teachers.
Teaching is a high-status job in Finland and teachers are accorded a great deal of professional independence.
It's a different philosophy from the system in England, says Mr Tuominen, which he sees as being built around a check-list of tests, league tables, targets and public accountability.
He describes the amount of testing as the "tail wagging the dog".
But before making any assumptions that the laid-back Finnish approach must be the way forward, you could just as easily look to the educational hot houses of Singapore or South Korea.
Their children also do better than those in UK schools, but with an entirely different cultural approach, based on long hours and relentless pressure.
This raises the question as to whether school systems, rather than shaping the next generation, simply mirror the society that's already there.
And in the case of Finland, Mr Tuominen says the Finnish school system is inseparable from the culture which it serves.
He says it's a "socially cohesive", equitable and efficient society, and it gets a consistently reliable school system to match.
This might sound as if countries are stuck forever with the school system that they've inherited.
But it's worth mentioning that there is nothing inevitable about Finland's success.
It's built on the foundations of reforms introduced in the 1970s and 1980s, which turned an ordinary school system into a world leader.
Russell Hobby, leader of the National Association of Head Teachers, picks out this "stability" beyond the electoral cycle as the key difference.
"In Finland there's a long-term approach to education policy that means plans remain in place for a significant amount of time, giving them a chance to work," he says.
"In England the opposite is true. The government is constantly tinkering with policy and there's an obsession with structure - such as grammar schools and academies - rather than a focus on evidence."
But there are no signs of cutting back on days or hours in the UK.
England, Wales, Scotland and Northern Ireland are already above the OECD average for the number of days taught.
And in England, this year's Budget in fact promised extra funding for extended days in secondary schools.
Pupils in England already get an average of 150 hours extra teaching per year than their Finnish counterparts.
The OECD's education director, Andreas Schleicher, says extra hours are linked to better results.
"You teach one hour of science more per week and you will see that reflected in higher average scores," he says.
But that doesn't mean it's going to be enough to catch up - because countries such as Finland, he says, can "deliver greater value in learning in fewer hours".
There is another big question raised by this balancing act between quantity and quality.
If there were shorter hours and longer holidays for schools, what would it mean for working parents and the cost of childcare?
There's also bad news on the homework front.
Even if the Finns don't need it, research suggests it makes a positive difference.
Prof Susan Hallam from the Institute of Education says there is "hard evidence" that homework really does improve how well pupils achieve.
"There is no question about that," she says.
A study for the Department for Education found students who did two to three hours of homework per night were almost 10 times more likely to achieve five good GCSEs than those who did no homework
So back to the late night arguments over unfinished homework.
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