This is likely to be one of my more heretical posts. I think heretical well chosen here since the notion that all demographic groups of significant size should ideally produce equal achievement test results is so broadly accepted and so little debated in American education as to be the equivalent of canon law. But I will open that debate here with three related theses: (1) I'm not sure the gap can be eliminated, (2) I'm pretty sure it can't by any other than unjust means, and (3) I don't understand why anyone thinks this would be a good thing to achieve in the first place.
The achievement gap is not some new discovery; its investigation goes back to the Coleman Report of 1966, and I have read historians' estimates of it having been far more pronounced, at least between Americans of African ancestry compared with Americans of European ancestry, in 1900 than it was in 2000; and indeed, if you want to see a gap, visit those two continents consecutively, and then reflect on how far the gap has narrowed in this country. But pretty intense efforts to close it have been taking place in American schools for 40 years, with discouragingly little evidence of recent success. I am not here asserting that it cannot be eliminated, merely observing that it doesn't appear that it will happen soon.
Achievement gaps are apparent even before children enter compulsory schooling (first grade), and unless we are willing to have some theoretical totalitarian government control all human reproduction and seize all infants at birth for placement in orphanages, we are unlikely to eliminate those gaps prior to first grade. So the only way to eliminate a pre-established gap would be to (1) eliminate all private education, including homeschooling and tutoring, and then (2) make unequal distributions of public educational resources (such as time allowed for and quality of instruction) so as to favor those who enter school behind, to enable them to catch up. Now look at the next bright six-year-old you see from an education-loving family, and then look at that child's mother or father, who has perhaps been diligently reading in bed to the child and playing educational games with her or him since she or he was a toddler; do you really want to discriminate against such young human beings so early in life, for the sin of growing up in a family that values education highly? Or are you going to wait until later to start handicapping that child so as to achieve your social vision?
My parents valued education highly; evidence of such was the subscription to National Geographic which appeared on the glass coffee table in our middle class living room, and I used to read it periodically as I was growing up. I remember reading about travelling on the Siberian Express when the Soviet Union was showing periodic glimmers of opening up to the rest of the world. During the Glasnost period of the 1980s, this journey sounded at first like one of the most romantic in the world; but through the account of the Western journalist undertaking the trip, we learned that it was one of the dreariest. Town after town, village after village, station after station, for 8000 miles (13,000 kilometres), through what in a non-totalitarian state should have been nine time zones, came and went, all exactly alike, the achievement of a Soviet state that prized equality, not just of opportunity but also of condition and outcome, before all else, at least in theory (less so in fact, we later learned).
Isn't the idea that there should be no achievement gap; that people of all races and ethnicities, of all backgrounds, linguistic, religious and otherwise, that all their family cultures should be rendered irrelevant and counteracted, and that all students should achieve exactly alike in every subject, a Soviet theory of education?