[Ras_]

Herein lies a major reason why early Finnish academic results are so uniform:

"“To be honest, we are not interested in a child’s academic skills at all. From our perspective that would be silly,” she said. The motor skills tests, by contrast, “show us a lot and help us diagnose any learning disabilities,” she explained. If a learning deficit was detected, it didn’t count against the child or banish her to a different classroom."

The article describes advanced methods of diagnosing learning decifits. Early interventions pay off big time. When a kid is found to have some sort of a problem, he/she will receive extra help within the normal classroom (e.g. teacher's aide). That prevents the social circles from breaking up and usually the better students learn even more by helping others. Few extra months of early help to make troubled students into average performers is reflected well in the PISA results. It has also societal effects (equality/equity). Best students might not benefit nearly as much from extra attention than worst, but in the western sphere gifted students are the main focus of attention. Finnish school system makes everyone average, for better or worse. But is not a bad thing when your average is still world class.