A New Jersey school is coming under fire after an elementary school class held a mock slave auction.

Fifth-graders at Jefferson School in Maplewood held the mock auction while under the supervision of a substitute teacher, NJ.com reported.

The website said the activity was not part of the curriculum in the South Orange-Maplewood School District.

“There was a sale of a black child by white children in the classroom,” Tracey Jarmon-Woods, parent of a student in another class at the school, told CBS New York. “If you’re demoralized — sold on a block in 2017 — it may affect you the rest of your life.”

“I’m disgusted, really disgusted a child was bought,” another parent, who was not named, told the station. “That doesn’t make any sense.”

The classroom’s regular teacher found out about the mock auction, which had been videotaped, after returning and sent a letter home to parents.

The teacher, who has not been named, said the incident would be used as a “teachable moment to elaborate on the gravity of this part in our history,” according to a copy of the letter obtained by The Maplewoodian website.

The school district sent a statement to the website saying it did not condone the activity. It blamed the substitute and said it would “look again at training and improved supervisory protocols for substitutes.”

The statement from Suzanne M. Turner, the district’s communications director, did not offer an apology.

Superintendent John Ramos later apologized at a school board meeting.

A letter sent to parents from the school said the video shows the students treating the auction “lightly.”

“The jovial nature of the video suggests that either there is a lack of understanding about the true barbarity of a slave auction, or a lack of awareness of how treating this topic comically is offensive,” the letter said, according to ABC New York.

The letter said the incident would be turned “into an opportunity for our students to learn and grow.”

The incident comes on the heels of an assignment at another school in the same district in which students made posters for slave auctions.

The district apologized for that incident as well.