You are simply mistaken: The immigration increase is so recent and so small compared to the population size that it can't have lowered the country's rankings.

You are simply mistaken: The immigration increase is so recent and so small compared to the population size that it can't have lowered the country's rankings. Pasi Sahlberg is the expert to listen to: "I don’t believe that the PISA results in Finland have anything to do with the language or the fact that Finland is more homogenous than others[.] Of course Finland has had fewer non-Finnish speakers or children who were born outside of Finland, but that cannot explain the progress in previous PISA studies or the declining results in maths." http://yle.fi/uutiset/osasto/news/finlands_school_system_the_new_nokia/6965192 http://yle.fi/uutiset/osasto/news/finlands_school_system_the... EDIT: Same misconception propagated by BBC in the article here (for "balance"?): "Success has been attributed to a traditionally high regard for teaching and reading, as well as a small, largely homogenous population" How would population size contribute to the averages? Who has attributed? In the BBC archives I can find that claim by some right-wing British think tank.