Earlier quoted context omitted.
this might help improve performance (though probably the effect will be much smaller than you think), but it doesn't explain the comparative weakness of american PISA results.
Why not? Sleep deprivation and long summer vacations will add up over time.
What many people who try to model the success of Finnish education system fail to see, is that Finnish society is highly equal. This is true between genders and especially between individuals from different social status and background. We work hard to give high quality education for everybody, no matter the cost.
This is the reason why sometimes I wonder how the projects that aim to export the Finnish school model to the countries like Saudi-Arabia can succeed, if the profound problems with the inequality deep in respective societies is not addressed first.
The PISA measures averages and it is in cutting the lower performing tail of the distribution where Finland excels.