In most countries, girls outperform boys in math. However, in the US, boys uniformly best girls. We are joined in the low-performing bottom three by Liechtenstein and Columbia. While we have the greater problem that math and science education in the US seriously lags that of other nations, we must face the fact that that lag is also the product of gender inequities.
Whether Zimmerman did so consciously or unconsciously, it's hard to avoid that race played a part in his decision-making, influencing his thoughts, attitudes and actions toward young, black males. There's a growing body of research documenting just how powerful implicit or unconscious biases can be.