A Texas teacher has apologised and been placed on leave after giving students an assignment asking them to list the positive aspects of slavery.
The charter school has also said sorry for the homework, which came in an eighth grade American history class.
It asked for a "balanced view of slavery" with the "positive aspects" and "negative aspects" of being a slave.
"To be clear, there is no debate about slavery. It is immoral and a crime against humanity," said Great Hearts Texas Academies superintendent Aaron Kindel on Facebook.
"We are removing from classrooms and will conduct an audit of the American history textbook in use, 'Prentice Hall Classics: A History of the United States'. If we deem this textbook imprudent, we will permanently remove it and replace it with a history book that accurately reflects our values."
Mr Kindel also said the assignment was limited to one teacher at just one campus, and he sincerely apologised for its "insensitive nature".
"The headmaster and teachers at the Monte Vista North campus will spend time with the impacted students to explain the mistake and engage them in lessons that are more thoughtful about this period of American history."
Approximately 800 students attend the Great Hearts Monte Vista school.