During Sunday’s presidential debate, Hillary Clinton blamed Donald Trump’s campaign rhetoric for an increase in tension in American schools. “Children listen to what is being said,” Clinton said. “And there’s a lot of fear. In fact, teachers and parents are calling it the Trump effect. Bullying is up. A lot of people are feeling uneasy. A lot of kids are expressing their concerns.” She spoke about a 10-year-old boy, Felix, who was adopted from Ethiopia. “This is the only one country he’s ever known. And he listens to Donald on TV and he said to his mother one day, ‘Will he send me back to Ethiopia if he gets elected?’ ”

Later, Clinton’s campaign tweeted out a moving letter from Felix’s mother, which called Trump’s campaign “threatening to my son physically, psychologically, and emotionally.”

Is the “Trump effect” real? And if so, how should educators respond to it?

It was the Southern Poverty Law Center that popularized the idea of a Trump effect. In April, SPLC released a survey of 2,000 K–12 teachers. More than half of them responded “yes” when asked whether they had heard “an increase in uncivil political discourse at [their] school since the 2016 presidential campaign began.” Two-thirds of the surveyed teachers agreed with the statement, “My students have expressed concern about what might happen to them or their families after the election.” One-third observed an increase in anti-Muslim or anti-immigrant sentiment.

The survey was far from scientific: Respondents were an overwhelmingly liberal group made up of teachers who are on SPLC’s email list or who visit their website. The organization is perhaps most well-known known for its research on hate groups. Another one of SPLC’s projects is “Teaching Tolerance,” a magazine and clearinghouse that “combats prejudice among our nation’s youth while promoting equality, inclusiveness and equitable learning environments in the classroom.”

Data from the National Center for Education Statistics suggest the long-range trend is that bullying is becoming less common. Latino, black, and Asian kids are actually slightly less likely to report that they have been bullied than white kids are. (Overall, 22 percent of American students describe themselves as the victims of bullying. The national data does not break out Muslim students.) Still, in the SPLC survey, teachers reported heartbreaking incidents that shouldn’t be written off. Here are a few of them:

“One of my students who is Muslim is worried that he will have to wear a microchip identifying him as Muslim.”

“A student has been called ‘terrorist’ and ‘ISIS.’ Another was told he would be deported if Trump wins.”

“Talking about Trump winning in our state, one student turned to another and said, ‘Goodbye, Kevin’ (because Kevin is Mexican).”

Several teachers who participated in the survey did report anti-Trump bullying, for example, “accusing each other that they are Trump supporters to isolate them from the social groups.”

Many teachers in the SPLC survey said they had directly addressed Trump’s rhetoric with their students, and sometimes put it into historical context—discussing Japanese internment, the Holocaust, or debating whether the Constitution would allow a President Trump to enact his various policy proposals, such as mass deportation and an anti-Muslim religious test for new immigrants.

But 40 percent of the survey respondents said they were hesitant to teach about the election. A teacher working in a conservative area reported, “In the past there have been calls to the superintendent or principal when teachers have expressed alternative views to the community. I need my job so I must walk this fine line.” Another wrote, “I … find myself being more cautious because of the extreme viewpoints of my students.” One teacher said, “I have completely avoided” talking about the election. “What I am struggling with is this … How do I discuss all of the divisive elements of the upcoming election and remain outwardly neutral?”

More than three-quarters of teachers in the U.S. are Democrats, but in a nation without a shared civics curriculum, Americans have historically expected public school educators to steer clear of political discussions. During the red scares between 1917 and 1960, tens of thousands of socialist, communist, and anti-war teachers lost their jobs. More recently, in Middletown, New Jersey, this spring, a high school teacher was asked to resign after showing his students a John Oliver video critical of Trump. Last month, a Long Island teacher was suspended after posting on her personal Facebook page, “This week is Spirit Week at Smithtown HS West. It’s easy to spot which students are racist by the Trump gear they’re sporting for USA Day.”

More conservative teachers, too, have faced criticism for political speech. In New York City in 2014, the teachers union participated in a march against police brutality; a group of dissenting teachers in Staten Island, where Eric Garner had recently been killed by police, protested by wearing NYPD T-shirts to class. The T-shirts angered the teachers union, which sent out a memo urging its members to “remain objective at all times.” But Mayor Bill de Blasio defended teachers’ right to express themselves, saying, “[H]ow you should comport yourself at your workplace, and the individual choice you make—that’s up to the individual.”

Jonathan Gold, a middle school history teacher in Rhode Island, wrote a thoughtful essay recently on the dilemma many educators face. “[W]hile I want my students to think for themselves, I also want them to learn to resist destructive ideologies,” he stated. He suggested that teachers put the 2016 election in historical context, asking students to read primary source documents and then discuss why George Washington was skeptical of political parties, or how the 1848 Seneca Falls declaration on women’s rights remains relevant today. “I’m not worried about appearing biased if my stance is against bigotry and in defense of moral reason and the scholarly use of evidence, logic, and research,” Gold wrote.

Gold, however, teaches at a private Quaker school. Public school teachers, particularly those without tenure, may be more hesitant to bring up the election with students whose parents do not share their political leanings—no matter how pedagogically sound their lessons are. In the meantime, we’ll be hearing more about the Trump effect. An ad from MoveOn highlights Trump-related bullying, such as a high school in Oregon that was vandalized with a banner reading “Build a Wall” and one in Indiana where student basketball fans chanted “Donald Trump” at players of color from an opposing school. The nation’s largest teachers union, the National Education Association, is supporting Clinton with a digital ad buy and direct mail campaign focused on the Trump effect.

The idea fits neatly into Clinton’s argument that Trump’s rhetoric is uniquely destructive to children. But perhaps it is children who see Trump most clearly for who he is. Many teachers who participated in the SPLC survey reported that students were confused as to why Trump was getting away with behavior and language that would get a child into trouble at school. One teacher wrote, “I don’t know what to say to these comments other than that in my classroom such things are not going to be tolerated, and if they continue, they are going to be sent to the office.”

Read more Slate coverage of the 2016 campaign.