The Finnish educators were just as surprised as the rest of the world by the results of the first PISA test. They had come out of nowhere to become the smartest people in the world. And that change happened extremely quickly—within a generation! 

When PISA came out in the early 2000s, it was met with skepticism and criticism. While even its creator, Andreas Schleicher, would admit that the test is not perfect, it is still the best out there for determining capacity for critical thinking and creative problem solving in reading, math, and science. For example, in the math section, students are asked questions that require not just plugging in numbers to formulas, but opinions about a problem or data presentation, with blank spaces to explain reasoning.