Parents of students attending Jefferson Elementary School in Maplewood, New Jersey, are outraged after finding out the school held a mock slave auction, CBS New York reports.

The incident reportedly took place in one of the school’s fifth grade classrooms earlier this month and led to a heated discussion later at a board of education meeting.

“I’m disgusted, really disgusted a child was bought,” one parent said. “That doesn’t make any sense.”

In a letter sent to parents, Principal Susan Grierson said the impromptu slave auction was conducted while the teacher was out for a medical procedure. A substitute was reportedly in charge of the class.

“The activity was not part of the curriculum, not part of the teacher’s assignment, not condoned by the classroom teacher, and not authorized by the district,” the statement said.

A school social worker is slated to speak with 5th graders on Tuesday.

This isn’t the first time to district has been under fire for its alleged assignments. Around the same time as the mock slave auction, another controversial lesson was given to students at South Mountain Elementary School.

The homework assignment has reportedly been included in the school’s curriculum for the last ten years. As part of the lesson, fifth graders studying the colonial era were expected to create an advertisement. One suggestion was a poster for a slave auction.

On one poster students allegedly produced, names of available slaves were listed. Another poster specified a cash only policy.

“I am mortified,” parent Susan Hoyn told reporters. “Those images actually hurt my heart.”

On Monday, Superintendent Dr. John Ramos reiterated that the incidents are not a reflection of the school’s ideologies regarding race.

“There was no intent to be provocative or demeaning,” he said. “The context is important to know.”

The district said it is also planning a town hall meeting to address the topic.