have an education system, with only a small group of people getting a decent education," Martin said. "When parents haven't been to school and are not literate. This is a big problem to overcome."
While well-funded, well-organized school systems produced the most able students, the studies found performance was not purely dependent on schools. The top performing students were those children raised in homes where books were present and they regularly were read to and saw others reading or engaged in math-related activities like games.
The math and science studies found many countries did better in teaching the basic rules of those subjects than in teaching their application, with students struggling to think of ways to use their knowledge to analyze a problem.
The rankings are based on 900,000 tests of students in their fourth year of formal schooling, typically aged 10 or 11, in countries that opt into the studies. The math and science study is conducted every four years and the reading study every five. They overlapped this year by coincidence.
Martin said the studies aimed to improve world educational standards by showing educators what other countries had achieved.
"One thing you can learn from these is what's possible," Martin said. "That comes as a shock sometimes, what students in other countries can actually do and the gap sometimes between what your students are achieving and what students in other countries are achieving."