A Boston-area fifth grade teacher who held a mock slave auction and used a racial epithet during instruction has been placed on paid leave, the local schools superintendent said.

Gregory L. Martineau, superintendent of the Public Schools of Northborough and Southborough, wrote a letter to parents on Wednesday that detailed the incidents and expressed his apology.

The teacher at Margaret A. Neary Elementary School in Southborough, Massachusetts, about 30 miles west of Boston, held a mock slave auction in January as part of a history lesson on the economy of the southern colonies, Martineau said.

As part of the impromptu auction, the educator made examples of two children of color who were at the front of the room, discussing attributes such as teeth and strength, the superintendent said.

Martineau said such instructional methods are unacceptable, as they can traumatize Black students and trivialize the horrors of slavery.

In April, the same teacher read from and discussed a book that’s not a part of the curricula, the superintendent said, adding that the teacher used the N-word, which Martineau said does not appear on the book’s pages.

The state teachers’ union did not immediately respond to a request for comment, and the local union could not be reached.

Martineau said he found out about both incidents on April 24. A meeting that included the teacher and the school’s principal was held in order to “be transparent with families and take responsibility for mistakes,” he said.

But the next day, the teacher, apparently having learned the identity of at least one of the students who complained about one of the two incidents, “called out the student,” Martineau said.

He said singling out the student was “not acceptable.”

The teacher was placed on leave and is undergoing “due process procedures” that could determine their status with the district, Martineau indicated. The school’s principal was placed on 10 days of paid leave in May, the superintendent said.

Sarah Alinovi, a parent who plans to enroll her child in Southborough Public Schools, expressed concern that similar incidents happened twice.

“If it happens over and over again, then, you know, it should be addressed,” she told NBC Boston.

Rahsaan Hall, president of the Urban League of Eastern Massachusetts, told the station that the incidents could provide a learning moment for the school district.

“They should certainly be intentional and proactive about developing practices and engaging the community on these difficult topics,” Hall said.

The superintendent apologized to the teacher’s students and took responsibility for “missteps” in the district’s initial reaction.

“I apologize for the events that took place in The Public Schools of Southborough,” Martineau said. “I acknowledge that there were missteps in this process that further complicated the situation. Ultimately, I am responsible for ensuring students are in safe and supportive learning environments.”

A plan that aims to ensure teachers have “cultural competency” is being developed with the goal of being implemented in fall. he said.

This article was originally published on NBCNews.com