A high school history teacher was forced to go on leave after he compared Donald Trump to Adolf Hitler. Frank Navarro, who has taught at Mountain View High School in California for 40 years, is a Holocaust scholar.

Quartz reported that Navarro was asked to temporarily leave the school last week after they received a complaint about what he was teaching in class. Apparently, the complaints were about a lesson where he discussed "remarkable parallels" between Trump and Hitler.

He talked about how similar their attitudes were, especially in using people against foreigners to win an election. Both leaders also promised to make their countries "great again."

Speaking to the San Francisco Chronicle, Navarro revealed that the parent accused him of saying that "Donald Trump was Hitler." He denied such claim, saying that "that's sloppy historical thinking."

"I think it makes sense," he said about the two leaders' similarities. "It's factual, it's evidence-based. It reminds students that history is real."

The school's principal, Dave Grissom, and Superintendent Jeff Harding believes that the lesson was inappropriate. "Regardless of their political affiliation, many of our students show signs of emotional stress," Grissom told parents last Friday.

He added that he is responsible for maintaining an "emotionally safe environment" for students. Moreover, he also wants to protect teachers and staff from unsubstantiated allegations.

According to Oracle Online, Navarro only wanted to show how present day events are parallel to history. He believes that his lessons were factually accurate since he was able to study the Holocaust in-depth.

Senior student Justin Allen did accuse Navarro of holding one-sided class discussions. He was enrolled in the teacher's first period Civics and Economics class. Navarro denied the accusations.

"I do agree with some of [Trump's] policies, and when I'd try to talk about it, [Navarro] just told me to shut up or said something super rude," the student said. "I like to treat people the way I want to be treated, and I would never treat a teacher that way. That's super disrespectful."