This week’s “Daily Journal” guest columnist is Kristen Blair, a North Carolina Education Alliance Fellow.

Recent episodes of school-related violence provide a disturbing snapshot of the consciences of American youth. Not only do these incidents spotlight brutal aggression and its ongoing threat to students, they also offer emerging anecdotal evidence that kids’ reasons for engaging in violence are changing, as are their perceptions of it.

Consider the following well-publicized trio of violent events this fall. In Charlotte, a 17-year-old male student attacked a school security guard viciously enough to send him to surgery. According to a school district spokesperson, the guard was breaking up a verbal altercation between girls when one of the girls’ brothers got involved and attacked him.

In Belleville, Ill., a student was beaten by two other teens while riding the bus to school. Denied a seat repeatedly, the victim pushed a backpack aside and sat down; the backpack’s owner began punching and choking him. Moments later, another student attacked. Video footage shows onlookers laughing, cheering, and clapping.

In Chicago, 16-year-old Derrion Albert was fatally beaten with wooden planks as he walked to a bus stop after school. Video clips reveal a mob scene with many onlookers; none saved him. Some bystanders reportedly laughed as he suffered.

Such episodes of violence, perpetrated against innocent students and an adult, have generated outrage. Much has already been said, and rightly so, about our culture of violence and the pernicious influence of gangs, poverty, and lax supervision on brutish adolescent behavior.

But there is another, perhaps more insidious, element that permeates these events: the way kids view acts of aggression. Youth have become increasingly desensitized to the effects of violence. In all three incidents, provocation was scant or nonexistent. True acts of vengeance, while immoral, have been with us since time immemorial. But free-floating rage among the young — displaced toward a random or convenient target? That is a newer, far more sinister beast.

Coupled with boredom, such anger reaches its boiling point. One 19-year-old college student I know who just finished three years at a Durham public high school, said, “I actually had people that told me they just felt like getting into a fight. They just wanted a break from their routine.”

What about the students who laugh and cheer? This is violence as spectator sport. Such malevolent joy smacks of schadenfreude, the German-derived word for pleasure felt at the sufferings of another. Make no mistake: this is not bystander apathy, bad as that is. It is exultation, or gloating, as another is traumatized. Schadenfreude may not be a novel concept, but it has traditionally characterized deviant adults, not mainstream children.

No longer. One of the laughers during the bus beating told the local Fox affiliate, “If you see a fight, every kid will laugh. Any fight you see we always laugh, it’s like adrenaline, we just laugh.” The student I interviewed said that, while he avoided the troublemakers at his Durham school, many other kids enjoyed the fighting: “Ten seconds after something happened, people are yelling, a circle forms. … For whatever reason, people do enjoy watching it, regardless of whether it’s ‘justified’ or [just] someone picking a fight.”

What can we do? Obviously, schools and law enforcement must ensure the safety of students and staff, seeking justice and punishing those who harm others. But we must also face the circle of mockers, gaping from the sidelines. Their hearts, like the attackers they cheer, have grown cold. No government program or initiative can fix that. In the end, warming the human heart and inculcating empathy is the work of parents. No excuses.