One reason inequality is self-perpetuating
Nick, it starts long before school, as teachers have known for decades. The article below reports, "children from families on welfare heard about 616 words per hour, while those from working class families heard around 1,251 words per hour, and those from professional families heard roughly 2,153 words per hour. Thus, children being raised in middle to high income class homes had far more language exposure to draw from."
Of course, we must hold teachers accountable for the way parents talk to their children in their homes before the children are even old enough to go to school. Accountability is good!