RE: … Singapore, which is a highly advanced and homogenous…
Not sure what you mean by homogeneous.
Singapore’s ethnic makeup is 75.5% Chinese, 15.1% Malay, 7.6% Indian, and 1.8% Eurasian/Other. Because of this diversity, Singapore is NOT considered a homogeneous country; instead, it is officially recognized as a multi-racial, multi-ethnic, and multi-cultural society.
Small, yes ( smaller than New York City in terms of population ), but homogeneous? Not really.
Your's is a very USA-centric view of "diversity."
Singapore does indeed have the racial breakdown you state. BUT its schooling (the topic here) is very specifically HOMOGENOUS, to ensure racial harmony and meritocracy.
All students are Singapore-born (except for a very small amount of foreign expats, usually at international schools). They are not cycling through thousands of illegal migrants from across the world.
from 1987 onward, the Singapore Govt mandated that core curricula are taught in English only. They have standardized schedules, standardized tests, standardized textbooks etc. - to ensure Singapore's famous meritocracy is preserved. By high school, students may choose one course for mother tongue instruction (much like US students can study Spanish, French, German) purely out of interest.
Singapore has licensed six madrassas for Muslim students (a very small percentage of students) who want extra religious study, but their core curriculum is the same as everyone else and is taught in English. The government ensures there is no specific racial or ethnic focus in these schools - although the majority tend to be Indian/Malay/Arab students. Even the madrassas are such that a Chinese student could enter and feel they belong there.
Starting in the early 1990s, Singapore Government created strict controls over Islamic studies, and who teaches it for thes specialized schools.
So again, unlike US schools in different states and locales, Singapore schools are extremely homogenous in their content, learning and social/civic education.