Could it be that African American students behave offensively more often?
Nah. Couldn't be.
The media trick is to state the proportional distribution of punishment, and not the proportional distribution of offenses.
They make it sound unjust, which is what they intend to do.
The lefties REALLY don't want to dig into that matter. Deep down, they know what they'd dig up: that black students generally receive LESS punishment for the same misbehavior. Go to the average inner city, predominantly black high school, and you'll see the BETTER behaved kids doing and saying stuff that would get them suspended from a lot of predominantly white schools. For starters, just imagine a kid (of any color) calling another student "nigger" at a predominantly white school.