In the United States, No Child Left Behind tied school funding to standardized test results, while also increasing the required number of standardized tests. These are already biased to favor white, middle and upper class boys, anyway. Teachers taught rote, that's basically it, to improve test scores, not learning. Before that, you can look for Lee Atwater's full interview about the Southern Strategy he did with The Nation. But in introduction to sociology, in college, it discusses how schools were designed to teach kids enough to understand and follow orders, not enough to question those orders. That makes for a hella compliant work force, military, police, FBI/NSA force. Other Western states followed suit, some got the privilege to pay for it, others the privilege of having it deducted from pay, through taxes, which is fine if it were to actually...educate.
I think graded levels are a terrible idea and that all schools should follow the Montessori model.