Are math teachers biased against white girls?

Researchers claim that math teachers are unjustifiably biased in favor of white male students. Interestingly, they are also biased in favor of black female students. The researchers wrote, "Once we take into account that, on average, black and Hispanic male and female students have lower grades and test scores than white males, teachers do not rate the math ability of minority students less favorably than students belonging to the traditionally advantaged category of white males."