Image copyright Reuters Image caption Shanghai has accelerated even further ahead in school tests

"It's mind boggling," says the OECD's Andreas Schleicher, describing the ambitions of Shanghai's education system.

The Chinese city has not only remained as the highest performer in this year's international Pisa tests in maths, reading and science, it has accelerated even further ahead.

So what makes it so successful?

Mr Schleicher, who runs the Pisa tests taken every three years, says Shanghai is engaged in a systematic, long-term project to improve education, as a way of transforming its economy.

"You can see from the minister down to the teacher in the classroom that this is their future and they believe education is the great equaliser," says Mr Schleicher, the OECD's education expert.

"That's why they make it prestigious to teach in a tough school," he says.

Ringing parents

A recent survey showed that teachers have a higher status in China than anywhere else in the world - and Mr Schleicher says they are not afraid of using this influence.

"Teachers call up parents at least fortnightly, they ring them on their mobile to check on how their children are working. They also tell them how to improve their parenting," he says.

Image copyright PA You scrape together the last money of the grandparents to pay for the education of your children. As a society you invest in education rather than consumption Andreas Schleicher, OECD

A characteristic of the Shanghai system is to require continuous professional training for teachers, with time away from the classroom.

"They want every educator on the front line to be a researcher, it's like wanting every doctor to be a research scientist," he says.

Another key to the high numbers passing exams is the expectation that they will.

The Shanghai system is not a "sorting mechanism" in which a diminishing number of people are allowed to progress through a narrowing funnel of education.

Instead it assumes that a large majority of pupils will be willing and able to succeed and that teachers are expected to make this possible.

This doesn't necessarily mean it's a "fair" system, he says. It's an intensely competitive meritocracy.

"If you are better than others, you're going to get better chances. That's the underlying belief," he says.

It isn't a place of safety nets.

And the intense competition means that an estimated 80% of students have private tutors.

Teacher 'generals'

There is also competition between teachers, says the OECD, with four grades of professional status.

Teachers are seen as "generals", able to make their own decisions, the OECD reports, and local government education officials are often drawn from the ranks of head teachers and teachers.

SHANGHAI EDUCATION 2009 Pisa: First place in maths, reading and science

First Chinese district to require continuous professional development for teachers

80% of pupils enter higher education

80% have private tuition

Almost 3,000 schools, 1.8 million pupils

The success of Shanghai and Hong Kong has often been put down to a Chinese historic cultural predisposition to education.

But this legacy is a mixed picture.

There is a longstanding belief in education as the route for social mobility, through institutions such as the highly competitive civil examinations system, which operated in China for centuries.

But in the 1950s the Chinese system had adopted a Soviet Russian model, and in the 1980s the country was still trying to get places for all children in primary and secondary school.

The current high-performing system has only been developed in the past couple of decades.

Raising standards

Within China, Shanghai has been seen as a pioneer in improving education.

It was at the forefront of raising teaching standards, such as the drive for an all-graduate teaching staff.

About 80% of young people in Shanghai enter higher education, far above the Chinese national average, and another reform was to create a local entrance system for the city's universities.

Image copyright Reuters Image caption Education is the path to a modern economy: China's Moon probe in Shanghai

There is no Pisa test result figure for all China, instead the rankings show a handful of urban hothouses such as Shanghai and Hong Kong.

It might not be representative of all China, but Shanghai is a relatively big place in its own right. It's bigger in population terms than countries such as Sweden, Greece and the Netherlands.

And in the next Pisa tests, to be taken in 2015, it is expected there will be enough data to show the performance of China as a whole country.

Mr Schleicher puts the success of Shanghai into the bigger picture of China and Asia.

There is a drive to re-invent the economy, switching from cheap manufacturing to hi-tech innovation.

"They're not afraid of losing jobs in the production sector, they want to move up the value chain, they want to upgrade their talent pool," says Mr Schleicher.

Even in the poorest areas of China they are pushing this educational upgrading, he says.

"So why are they doing it? It's an intriguing question. I guess it comes to how society is balanced, the present against the future. What you have in Asian societies is the willingness to sacrifice the present for a better future."

"You make long-term investments in yourself and in society. You scrape together the last money of the grandparents to pay for the education of your children. As a society you invest in education rather than consumption.

"All of those things are very strong in Asia. There is the belief that to have a better future you have to make compromises today."