(CNN) A Texas charter school is apologizing after a teacher gave an assignment to an eighth grade American History class, asking students to list the positive aspects of slavery.

"When I first read it, I thought, this was b.s.," said Great Hearts Monte Vista eighth-grade student Manu Livar.

Students in the class were supposed to complete an assignment on the "positive aspects" and "negative aspects" of the life of slaves, giving a "balanced view." Manu said his teacher told them to draw on information from their textbook and "stuff that we could think of the top off our head."

It was a precursor to the class reading former slaves' accounts of their lives in slavery.

When his mother picked Manu up, he showed her the assignment; she immediately sent a picture of it to her husband.

"What the hell is this revisionist history lesson trying to achieve here?!?" said Roberto Livar, Manu's father, who posted it to Facebook on Wednesday.

Since then, the superintendent and headmaster of the K-12 public charter school, where approximately 800 students attend classes, have met the family and other concerned parents, and the teacher has been placed on leave.

"To be clear, there is no debate about slavery," Aaron Kindel, the superintendent of the Great Hearts academies in Texas, wrote Thursday on Facebook. "It is immoral and a crime against humanity."

Kindel also said the assignment was given by only one teacher, and he apologized for its insensitive nature.

Great Hearts Monte Vista schools are going a step further and removing the textbook being used, "Prentice Hall Classics: A History of the United States," until it reviews the material, Kindel said.

"The worksheet in question was not created by, endorsed, or encouraged in any way by Pearson," a spokesperson for Pearson, parent company of Prentice Hall, told CNN. "We do not support this point of view and strongly condemn the implication that there was any positive aspect to slavery."

Although school officials say they will sit down with the students in the class to "explain the mistake," Manu says he's getting some backlash at school.

He says some at school have actually attempted to defend the assignment.

Roberto Livar says that's unacceptable, wondering what if the assignment had been to weigh the positive and negatives of human trafficking.

"We'd have large support across the board (against the assignment)," he said.

CNN has reached out to the teacher for comment.