Americans may have spent the summer focused on race and police brutality, but racial disparity isn't only present in the criminal justice system.

New research shows that black students are far more likely to face discipline in school, despite not acting up any more frequently than white peers — despite the fact that there's no significant difference in behavior between black and white students. It's a huge gap: African-American girls, for instance, are six times more likely than their white counterparts to be suspended.

Consequently, it's about way more than dropped grades and extra detentions. Missing enough class can put students further behind their peers, making school more difficult and potentially having a huge impact on future earnings.

National Journal

The numbers: African-American girls make up about 17% of female students in the United States, according to the National Journal. Yet in the 2009-2010 school year, they made up 37% of girls given an in-school suspension and more than half of girls an given out-of-school suspension.

The disparity doesn't stop at punishment handed down by schools themselves — 31% of female students referred to law enforcement were African-American, as were more than 42% of those subject to school-related arrests during that time period.

You may assume that this disparity is because black students cause more trouble in school. But an Indiana University study from earlier this year revealed that there is no racial or ethnic difference in behavior among students, and that even poverty has only a small effect on behavior differences. And these racial disparities hold no matter the socioeconomic standing of the students in question.

"There is simply no good evidence that racial differences in discipline are due to differences in rates or types of misbehavior by students of different races," the report says.

What it means: Oftentimes, a large number of suspensions can be the difference between a college acceptance and heading to the workforce with a high school diploma or even the difference between graduating high school and dropping out.

A study released last month by the NAACP Legal Defense and Educational Fund and the National Women's Law Center shows that a college degree for an African-American woman means, on average, $657,000 more income over the course of a lifetime.

Suspensions mean missed class, a poor disciplinary record and other potential roadblocks to graduation — one student interviewed by the National Journal was placed in a transitional academy that may have irrevocably delayed her learning process.

"My whole life has been affected by a fight that I was in when I was 14," Tiambrya Jenkins told the National Journal. "It's not something that you can take back and not something that was premeditated, and I still have to deal with the consequences every day."

If high schools truly care about all their students: They've got to face the facts. Not everyone is being treated equally.