The school-to-prison pipeline, explained in 3 minutes

In October 2015, a cellphone video of a white police officer flipping over an African-American student in her desk went viral. The police officer, who was later fired, is one of the thousands of officers who have been brought into schools since the mid-1990s in an effort to prevent acts of violence like the 1999 shooting at Columbine High School.

In reality, the presence of these school resource officers, as they're called, means that students at these schools are far more likely to end up in juvenile court for relatively minor offenses. The addition of school resource officers combined with existing racial disparities in school discipline help feed what advocates and researchers call the "school-to-prison pipeline."

School resource officers also operate in a system in which students of color are far more likely to be punished at school than their white peers. While black children made up 16 percent of all enrolled children in 2011-'12, according to federal data they accounted for 31 percent of all in-school arrests.

Several studies have looked at the relationship between race, behavior, and suspension, and none has proven that black students misbehave at higher rates. A study in 2002 found that white students were more likely to be disciplined for provable, documentable offenses — smoking, vandalism, and obscene language — while black students were more likely to be disciplined for more subjective reasons, such as disrespect.

Check out the video above to learn more about the school-to-prison pipeline and what some school districts are trying to do about it.