Read this from HN in 2011, was interesting. But I take Feynman's conclusions with the grain of salt, and most comments here are near conspiracy theories. Here's why.

Education in the older epoch that his informers mention, was much smaller in scale. Brazil's illiteracy was at ~65% in 1930, at just <50% by 1960, if I remember correctly. So both common schools and secondary education (college/university) were expanding at the time. And that's the reason.

If you expand education, quality inevitably drops. The lower social strata that are reached by education won't get as good teachers as earlier. You may be able to write good schoolbooks, like mathematicians in the USSR did, but there's still last mile problem, the teacher. Most teachers are not bright enthusiasts, often times they're underpaid and burnt out after ages of teaching. The few enthusiasts and visionaries, are exceptions -- at least this is what I read from one recent study -- and their recipies aren't reproducible.

From what I've read, better universities usually have less students per teacher. This way a teacher can engage better and actually care what the student does. This requires more money poured in the system and less corruption.

(For non-Western countries, money shouldn't be a big problem, they're spending smaller share of GDP on education. But modern beliefs tell that everything should be "efficient", and governments don't want to spend more, instead they insist they need to "digitize" education, and then somehow it will make breakthroughs.)

But also, if you want to play god and pour money from the education ministry into schools or colleges/unis, these streams may actually never reach the file and rank teachers.

Last note: elite school/uni material won't work in lower level ones. I taught in the university where some graduation projects were published in journals for young researchers, and teachers were publishing in not top ranking, but high ranking serious ones. Some courses included work on good older papers (in English, a foreign language).

There, you could easily dismiss students who just want a grade and a degree as noise.

But take a city further from the capitals -- even in good college students will struggle and not able to process it. Not because further on the periphery people are dumber -- simply because most brightest students went to the best unis in the capitals.

In the elites, it's easy to argue to shrink education to keep only the bright guys, like in the XIX century. Well, it doesn't work this way -- you need to educate lots of people to find more bright ones.

So, who, what and how will teach those less bright guys? A big open question to me.