I must study politics and war that my sons may have liberty to study mathematics and philosophy. My sons ought to study mathematics and philosophy, geography, natural history, naval architecture, navigation, commerce, and agriculture in order to give their children a right to study painting, poetry, music, architecture, statuary, tapestry, and porcelain. – U.S. President John Adams

The latest Program for International Student Assessment (PISA) scores are out for 2018, and once again Korea’s performance declined.

According to the OECD, which administers PISA, in Korea, average reading, mathematics and science scores are roughly the same as they were in 2015 and well below what they were in 2009 and 2012.

What explains the decline? To answer, we have to first understand what was behind the peak scores.

The OECD survey about the school climate in Korea notwithstanding, it was clear from my time in Korea in 2014 when I was on an Eisenhower Fellowship that enabled me to spend nearly a month studying Korea’s education system that the strength of its students’ performance was not based on its public schools.