It's the curriculum, folks. IQ is just the quality of the slate brought to the table.
Singaporeans here excel in the same classrooms that other students are failing in. Take a look at merit college admissions in California. Then take a look at prison admissions. Smart people will succeed in any system.
If those Singaporeans here in the US are excelling, their scores are not showing up on the NAEP or the internationl tests.
Meeting or excelling at an exemplary curriculum is something else entirely.