PISA worldwide ranking of math, science, reading skills - Business Insider:
"The Organization for Economic Co-operation and Development (OECD) released the results of its 2015 global rankings on student performance in mathematics, reading, and science, on the Program for International Student Assessment, or PISA.
The PISA is a worldwide exam administered every three years that measures 15-year-olds in 72 countries.
About 540,000 students took the exam in 2015.
The US saw an 11-point drop in average score for math, while remaining relatively flat in reading and science."