Finland is 3rd in the world with student performance. behind China and Sweden I think.
Taking kids at 4 is "getting them while they are young" because they are so impressionable. It is at this stage that you teach kids to conform and subordinate unquestioningly to authority, this is carried through life.
I can think of two different experiments that have been done that relate to this.
There was the Blue Eye Brown Eye experiment. Kids with Brown eyes were told they were inferior to people with Blue eyes. The kids knew it was a sort of demonstration. The teacher would always favour the blue eye'd kids. They got to drink first from hte water fountain ect, praised and so on. Eventually the Brown eyed kids started to complain. The teacher then lied to the kids and said blue eyed people were actually superior in ways, which many people think is cruel and I can see why, but the result was that brown eyed kids started to do worse in their exams tests, and had worse rebellious behaviour. The blue eyed kids did better in pretty much all ways but notably, they started to believe their own superiority.
Here was a teacher that was able to create racism with her class in no time based solely on eye colour. These were older than 4 years old too. They just submitted and believed everything. That's my point. They were literally turned "eyeist"
The other was the Milgram experiment, one person in a rooom with a button, they ask questions into a mic, they think there is another person next door. If the 2nd person answers wrong, the first person administers a shock and the volts are incremented with each wrong answer.
Because a guy in a white coat told them, he was no scientist just an actor with no authority, the people kept sending shocks even after they suspected they had killed the other person (who was just an actor in the next room screaming and moaning).
That's grown adults doing what they are told and were prepared to kill someone because they are predisposed to subordination and authority, most likely from education at a young age