The class tittered at that remark, but then fell into shock as he continued: “Calling someone a boomer is like calling someone a” racial slur, Mr. Gade was quoted by the newspaper as saying.

Molly Kruse, a 21-year-old senior who was in the class, said that the word jolted her.

“I said, ‘Dr. Gade, I don’t think you should be using that word here,’” she said in an interview.

Ms. Kruse said she was too stunned to remember the professor’s response, but other students later told her he quickly moved on from the topic. Ms. Kruse, however, said she walked out of the class at that moment and went to the dean’s office. Other students later joined her.

Miles Francisco, a senior and co-director of the Black Emergency Response Team, a student group, said it was not the first time a professor at the campus had used the slur in class and justified uttering it “for educational reasons.”

Those instances have been infuriating, but Mr. Gade’s use of the word was particularly upsetting, he said.

“Here, it was, ‘Let’s compare ‘boomer’ to a word that’s rooted in historical violence,” said Mr. Francisco, who was not in the classroom. “This was a bit more jarring because it can’t even be excused as, ‘Oh, I was using it educationally or it was in the literature.’”

Image Peter Gade speaking at a Gaylord College event in 2013. Credit... Austin McCroskie/OUDaily

The Black Emergency Response Team, an organization of black student leaders with the stated mission of confronting racism on campus, said on Twitter that it expected “full action to be taken against the professor and college.”