As I prepare for the coming school year, I’m planning lessons and looking forward to seeing new faces in my classroom. But something that happened over the summer is also on my mind.

Our nation’s bifurcated reaction to the tragedy of Trayvon Martin’s death and George Zimmerman’s subsequent acquittal cries out for each of us to rethink race, youth, guns, crime, and justice.

One group of Americans believes, with the jury, that according to Florida law, George Zimmerman’s actions were justified beyond a reasonable doubt. Another group is left protesting or shaking our heads in despair: What went wrong? And what now?

As our president tried to explain, the context of Trayvon’s death is deeply relevant to our reactions: What does each of us think when we see a young black man wearing a hooded sweatshirt? Do we see a predator, a son, a reflection of our younger selves?

What we see leads to how we will “reasonably” react when we encounter a teenage boy in a hoodie: Will we feel it reasonable to clutch our purses and cross the street? Will we find it reasonable to look into his eyes and say hello? Or will we, God forbid, find it reasonable to get out of our car, unsheath a weapon, confront the teenager, and get involved in an altercation leading to his death?

I teach in a racially mixed middle school in New York City. So when I see a photo of Trayvon in his hoodie, even one of the photos in which he’s trying on the persona of a tough guy, I see a young man who could have been my student. I see someone to whom I have a sacred responsibility.

Although a hoodie is just a sweatshirt, since Trayvon’s death hit the news, hoodies have come to signify the stereotype that young black and Latino men are dangerous. It’s the stereotype that’s dangerous. Unless we unlearn persistent prejudices in a safe space—like a middle school classroom—they are likely to thwart us for years to come, in ways we may not expect.

In Claude Steele’s remarkable book Whistling Vivaldi, the author describes what social psychologists refer to as “stereotype threat”: When people worry about personifying, or “fulfilling,” negative stereotypes, they underperform. In the case of girls, for example, this means that when they think about negative stereotypes of their gender before, say, taking a math test, they are more likely to do poorly, because of the deep cultural message that girls are not as good at math as their male peers.

Because of stereotype threat, young men and women of color with lots of academic potential tend to do worse on academic assessments when they’re in environments where they are concerned that they may fulfill negative stereotypes about their race. This is true even when nobody is overtly voicing those prejudices. Understanding the reasons behind stereotype threat—and understanding how to erase its effects—holds tremendous implications for teachers. As Steele points out, we are uniquely positioned to change school environments so that our students—our Trayvons, Thomases, and Theresas—become much more likely to succeed.

Stereotype threat thrives in situations in which students don’t feel valued or comfortable just as they are. Teachers can help by creating environments of warmth and understanding. But just being supportive is not enough. Because stereotype threat leads to dire academic and life consequences, it’s my responsibility to set the bar high for all my students, teaching them well and communicating that they matter, as does their work.

My broadest hope is that my students will meet many people worthy of their trust, and that they will greet them with a sense of confidence and curiosity that they have been allowed to develop in the safe walls of my classroom.

Read about Launa Schweizer.