Finland
is a relatively homogeneous country -- as of 2010,
just 4.6 percent of Finnish residents had been born in another country, compared with 12.7 percent in the United States. But the number of foreign-born residents in Finland doubled during the decade leading up to 2010, and the country didn't lose its edge in education. Immigrants tended to concentrate in certain areas, causing some schools to become much more mixed than others, yet there has not been much change in the remarkable lack of variation between Finnish schools in the PISA surveys across the same period.