The OECD conducts an assessment every three years of education systems worldwide by testing the skills and knowledge of 15 year old students in science, reading and mathematics (plus collaborative problem solving and financial literacy). 72 countries are evaluated, with 540,000 students put under the spotlight of a two-hour test. Our infographic below combines the median scores for each country or region in the three core test areas to show which performed to the highest overall level. With a mean score of 1,655, Singapore tops the list ahead of Hong Kong and Japan in second and third respectively. The U.S. just scraped into the top 30 with a below OECD average score (1,476) of 1,463.