The usual explanation, tested
It's not just money
Black students statewide score below low-income students of all races, so income alone cannot explain the gap.
The most common explanation for race gaps is that they are really income gaps. Texas data lets us test that directly, because the state reports results for low-income students of every race.
Black students overall, including every middle-class and wealthy Black family, score below the all-races poor average. No mix of poor and non-poor students can average out that way if income were the whole story.
Something at least as large as income's effect does not reduce to income. The strongest candidates in the research: family wealth (which the school-lunch flag can't see, and which differs sharply between Black and White families at the same income), school treatment such as the advanced-course gatekeeping documented on this site, and expectations.