Nearly a week after allegations surfaced at a charter middle school on the campus of Howard University that three teachers were terminated because they wanted to teach more black history, the school’s board of directors issued a statement denying the claims.

According to the statement released Tuesday, the teachers from Howard University Middle School of Mathematics and Science resigned Jan. 22, and their resignations were accepted Jan. 27.

“The teaching of African and African American history and culture was not a factor in the acceptance of the resignations,” the statement said. The curriculum at the school includes lessons designed to foster an “enduring understanding of African cultural systems,” the statement said.

It went on to say that the school’s chief academic officer, Angelicque Blackmon, who has come under criticism from parents for her handling of the matter, was recruited through a national search and has a “long track record of engaging African American students and teachers in culturally responsive STEM education,” or science, technology, engineering and math education.

Parents at the school have waged a public campaign since last week to find out what happened to the teachers and why they left so abruptly. Adilah Bilal, president of Parents in Action, a parent group at the school, said the social studies teachers had told the group that they were planning to resign. She said they were frustrated because they wanted to include more African history in a curriculum that focuses heavily on Greek and Roman history, but they claimed the administration did not support them.

The parents had hoped to hire a mediator to resolve the dispute, Bilal said. But before they could do that, she said, the teachers were given termination papers in front of students and made to leave in the middle of the school day.

Scores of students staged a protest on the main quad of Howard University on Monday, asking for “New social studies teachers that will be treated with respect.” The D.C. branch of the NAACP announced an investigation into the matter later that day.

Akosua Ali, president of the branch, said the preliminary finding is that the teachers were not discharged for teaching black history, but she cited concerns about how the teachers were treated and about the overall learning environment at the school.

The teacher departures are emblematic of a larger problem with turnover among faculty members and administrators at the school, parents have said. Wayne A.I. Frederick, a member of the middle school’s board of directors, said that the board will begin to address the concerns “in a comprehensive manner” this week.