School funding not always linked to results
Investing in education is one of the most promising ways for countries to secure their future.
And yet, there is a surprisingly tenuous relationship between the amount of money spent per student and the results of international Pisa tests, at least when comparing relatively wealthy nations.
South Korea is one of the highest-performing OECD countries, but spends well below the average per-student expenditure.
Students in Poland, which spends around $68,000 (£52,000) per student between the age of six and 15, perform at the same level at age 15 as the United States which spends over $115,000 (£89,000) per student.
That means despite spending much more money the US does not gain any advantage in results.
More broadly, the world is no longer divided between rich and well-educated countries and poor and badly educated ones and success is no longer just about how much money is spent, but about how that money is spent.
The teacher-pupil ratio in China and the United States is almost identical. But the Chinese chose much larger class sizes than are seen in the United States, up to twice the size. That enables the Chinese to give teachers much more preparation time, lesson-development time, time to collaborate with other teachers, time to work with parents and time to tutor students who are behind in class.
It is the same cost, but very different approaches. Chinese policymakers traded larger class size for more professional collaboration and more favourable working conditions for teachers, while American policy-makers opted for smaller classes, lower salaries and less time to plan and collaborate.