Less than half the countries listed are NOT part of the OECD. Out of nearly 200 countries, 60% they chose were members of the OECD. The are 34 members, making them below 18% of all countries in the world. 60% of answers in this list is just from 18% of countries in the world.
Math and science appear to be strong in the school system. There are problems with the education system, and many people drop out of high school, but overall there is knowledge in these two subjects.
Also don't forget that the school system is very strict in Vietnam, similar to several other East Asian countries, meaning that there is less tolorence towards slacking off in school.
Also don't forget that the school system is very strict in Vietnam, similar to several other East Asian countries, meaning that there is less tolorence towards slacking off in school.