This week's fact-finding visit to Shanghai by Elizabeth Truss, England's education minister, along with a delegation of the country's school leaders, is confirmation of the Chinese city's status as the new darling of global education tourism.
At one time, the world's education policymakers beat a path to Helsinki, Finland, to learn about the benefits of highly qualified teachers. Today, they are jetting to China's largest city for lessons in teaching maths.
On the surface, Shanghai's credentials appear more than impressive: it finished top - ahead of 64 other school systems by a large margin - in maths, science and reading, according to the latest edition of the Programme for International Student Assessment (Pisa). The difference between its score in maths and the average for the industrialised world is now the equivalent of nearly three years of schooling.
But despite that seemingly incredible feat, a serious debate is continuing about whether Shanghai's school system really deserves the plaudits it is now receiving and whether it is wise for other countries to draw inspiration from it.
First, there are discussions about whether there are cultural or even genetic explanations that the West would find it hard, if not impossible, to replicate. Of the top six Pisa places for maths, five were taken by cities or countries with majority Chinese populations. Ethnic Chinese students also regularly outperform other groups when they attend schools in Western countries.
But Andreas Schleicher, deputy director for education and skills at the Organisation for Economic Cooperation and Development (OECD), which runs Pisa, argued that culture was "at best one of the dimensions [of educational success]" and that "you can live in a very similar culture and come out with very different results".
The extensive use of private tutoring is likely to be another significant dimension of the success of all East Asian systems. That again raises the question of whether it is sensible to assume that a good Pisa score is necessarily all about the quality of schools.
Then there are the more specific concerns about Shanghai. Critics say it is unfair to compare the performance of China's most dynamic and wealthy city with entire nations; that you may as well judge rural China against London.
But Pisa analysis suggests that Shanghai's strength is that its schools benefit students of all backgrounds: the children of cleaners in the city outperform the sons and daughters of doctors and lawyers in the UK.
In the words of Mr Schleicher: "The biggest performance gains in Shanghai have not been at the top. They have been in the migrant groups and the poor schools."
But one academic - Tom Loveless, a former teacher and Harvard University policy professor - has cast serious doubt on whether the city's poorest young people are properly represented in the Pisa results.
Writing for the Brookings Institution, a respected American thinktank, he notes that the children of Shanghai's millions of rural migrants will not have the official residency status needed until very recently to attend the city's high schools under China's controversial hukou system.
Pisa reports that 90,796 of Shanghai's 108,056 15-year-olds are enrolled in school. But Professor Loveless queries this figure because it is approximately the same as for Portugal, which has less than half Shanghai's overall population.
China's "child policy" cannot explain the difference, he writes, because European families also have low birth rates, so it appears that more than 120,000 Shanghai migrant 15-year-olds have been filtered out of the city's Pisa results.
Mr Schleicher responded to Professor Loveless' comments by saying that Shanghai's resident migrants were covered by Pisa and that the hukou system had "long changed".
Zhang Minxuan, director of Shanghai Pisa, also hit back, stating that the figure of 108,056 included 29,966 migrant students, and that the 15-year- old age group was under-represented among migrants to the city. He also said that these migrant students still outperformed students from all other Pisa participants in all three subject areas.
Whomever Shanghai schools taught, Mr Schleicher was clear that they were successful because they treated teaching as a science rather than an art.
"They have a platform where people share their lesson plans," he explained. "You score points according to the number of people who use your plans. They build these over years through a process of continual refinement.
"The more people who believe in your ideas, the more popular you will become as a teacher. It is actually good for your career. This is how a profession really expands, in a very careful thoughtful way, how every child can learn."
Ray Tarleton of England's National College for Teaching and Leadership visited Shanghai last month and found an emphasis on subject knowledge among its teachers.
"The Chinese waste no time on teaching theories of education," he said. "While they may not be better teachers than their English counterparts, they have the advantage of knowing much more about their subject. And it shows."
It is an approach that will doubtless have impressed Ms Truss and her fellow delegates if they witnessed it this week. But it would also be worth them noting another comment by Mr Schleicher: "Shanghai is a sort of education Mecca in China. It is likely to represent the peak of Chinese education performance, not the average."