The Department of Education released a report in May called “The State of Racial Diversity in the Educator Workforce.” Another title for it might be: “The Incredible Whiteness of Teaching.” Most students in public schools are not white, but more than 80 percent of public school teachers are. And despite decades of effort, educators are still struggling to narrow the achievement gap between white students and black and Hispanic students. What can white teachers do to better teach across cultural and economic divides? Columbia University Professor and author Christopher Emdin thinks he has a solution: a new approach to teaching that’s about meeting each student on his or her own cultural turf.