From a New York Times guest essay by Adam Grant headlined “Kids Benefit From Having One Teacher Twice”:

Which country has the best education system? Since 2000, every three years, 15-year-olds in dozens of countries have taken the Program for International Student Assessment — a standardized test of math, reading and science skills. On the inaugural test, which focused on reading, the top country came as a big surprise: tiny Finland. Finnish students claimed victory again in 2003 (when the focus was on math) and 2006 (when it was on science), all while spending about the same time on homework per week as the typical teenager in Shanghai does in a single day.