Kathy Maher, a sixth-grade teacher in Newton, Mass., said that election years usually presented an excellent opportunity for students to observe the virtues of the American democratic process. But this year, she said, she worries about the school’s mock-debate season, when someone will have to play Mr. Trump — a candidate who, if he were a student, would be sent straight to the principal’s office.

Her school has a program encouraging students to speak up if they see someone being mistreated, Ms. Maher said, and for that reason, she has felt obliged to address the subject of Mr. Trump.

“I try really hard, when we discuss politics, to take a balanced view,” she said. “But I felt I had to say something this time, because the things Donald Trump says wouldn’t be tolerated in our schools. He bullies people, he name-calls, he makes fun of people because of their race, their ethnicity and the way they look.”

What about students whose parents are Trump supporters? “I say, ‘People might like some of the things that Donald Trump stands for, but there are better ways of saying it,’” Ms. Maher said. “I did say that some people like that he says things for shock value, like the crazy old uncle who just says whatever he wants. But as an educator, I can’t support that. It’s not funny — it’s mean.”