Baltimore would be a counterexample. They spend $22k per student, with a student-teacher ratio of 15 to 1. This still results in remarkably poor performance, with only 8% of students proficient in math and 22% in reading.
Culture and genetics would be next obvious explanations.
> obvious explanations
I'd want to assess a few lessons first.
Genetics lmao come on man.
The mean IQ score is 100... Unless you are in some elite school for the top 10% it is not reasonable to use genetics as a justification. It sounds more like a thinly veiled form of specifically American racism.