Another piece of evidence has emerged supporting the importance of minority teachers in the classroom. A scholarly study picked up by The Atlantic found that an increase in the number of African-American teachers was associated with a decrease in pregnancies among African-American teenagers.

Significant decreases in the pregnancy rate among African-American students was dependent on a "critical mass" of African-American teachers -- at least 20 percent of a school's staff. As we recently reported, the 2011-2012 School and Staffing Survey found that the number of minority teachers has not kept pace with increases of minority students in recent years, which makes it even more likely that schools will struggle to reach that "critical mass" in years to come.