A New Jersey school district is under fire for the second time this month after a substitute teacher allowed fifth-graders to “sell” a fellow student during a mock slave auction that was filmed.

The incident was reported at Jefferson Elementary School in the South Orange Maplewood School District, the same district in which students studying colonial America this month at another school drew slave auction posters and hung them in the school’s hallways.

In the latest incident, students studying the triangular slave trade presented a project in which they held a mock slave auction and asked fellow classmates to participate, according to NJ.com. They filmed the project, which was part of their own unit on colonization.

The class was being led by a substitute teacher while their regular teacher was out having dental surgery. When she returned and learned about the project, she sent a note to parents.

"While I understand the creative effort, and the impact it had upon the students who viewed this, I used it as a teachable moment to elaborate on the gravity of this part of our history," the teacher wrote to parents in the letter, obtained by NJ.com. "I was concerned about the students who viewed and participated in this re-enactment and would like to convey this event to you so we can address the students' perceptions as a whole."

Some parents were angry and upset over the issue.

"There was a sale of a black child by white children in the classroom," parent Tracey Jarmon-Woods told CBS New York. "If you're demoralized -- sold on a block in 2017 -- it may affect you (for) the rest of your life."

“I’m disgusted, really disgusted (that) a child was bought,” another parent told the news station. “That doesn’t make any sense.”

A school district spokeswoman said administrators are looking into better training and “improved supervisory protocols” for substitute teachers.

“The activity was not part of the curriculum, not part of the teacher’s assignment, not condoned by the teacher and not authorized by the district,” Suzanne Turner told NJ.com.

The latest controversy comes on the heels of the slave auction poster debacle at South Mountain Elementary School, where students were told to draw events that would have occurred during their assigned colonial time period. The assignment included "a poster for a lecture, speech, protest or slave auction."

The posters were initially hung around the school, but were taken down after complaints from parents and members of the community.

Dr. John Ramos, superintendent of the school district that includes both schools, said earlier this month that the district will rethink its colonial America project. Ramos told CBS New York on Monday that the district is planning a town hall event with parents and students to discuss the topic.