Chalkboard in the lobby at Ballou High School in Washington. (Bonnie Jo Mount/Washington Post)

The superintendent of D.C. schools confirmed Thursday that her office has been cooperating with federal investigators as part of a probe into the city’s public education system following revelations of inflated graduation rates.

“I am aware of the FBI’s investigation,” State Superintendent of Education Hanseul Kang said Thursday at a D.C. Council hearing. “We are cooperating with any requests we receive.”

When pushed by council member Elissa Silverman (I-At Large) to describe the investigation, Kang declined to answer. She said she has not met with the FBI.

“My understanding is that because it is an ongoing investigation, I do not have any information that I am able to share,” Kang said.

A spokesman for Kang’s office would not answer additional questions after the meeting.

The brief interrogation unfolded at a D.C. Council oversight hearing into graduation practices in the nation’s capital. The five-hour hearing — convened by Council member David Grosso (I-At Large), who chairs the Education Committee — focused on a city-commissioned report that discovered one-third of D.C. Public Schools’ graduates in 2017 received diplomas despite missing too many classes or improperly enrolling in remedial classes.

The Office of the State Superintendent oversaw the city’s investigation, which also uncovered a culture in the school system that left teachers feeling pressured to graduate students who did not meet city qualifications.

Schools Chancellor Antwan Wilson and Scott Pearson, executive director of the city’s charter school board, testified Thursday that they have not spoken with the FBI and learned about the investigation from the media.

The nature of the inquiry is unclear, but a current and a former D.C. government employee with direct knowledge say the investigation involves the FBI and the Inspector General’s Office at the federal Education Department. The city’s Inspector General’s Office is also participating.

The sources say the investigation is focused on Ballou High School, where allegations were first raised about diplomas being wrongly awarded to chronically truant students.

Grosso, who has served on the council since 2012, said Thursday he was frustrated to learn that the school data he had been receiving for years was not an accurate representation of student achieve­ment.

In an unusual move, Grosso required Kang, Wilson and Pearson to take an oath to tell the truth Thursday, something the council member said he doesn’t typically do.

“We’re in a tough spot in this city right now because the reality is that we weren’t honest,” Grosso said. “And when you’re not honest, it’s hard to recover.”

The council members grilled the education leaders on how the graduation scandal happened and what they were doing to fix it.

The council members asked why high truancy rates and low standardized test scores didn’t prompt more scrutiny as the city celebrated increasing graduation rates in recent years. They wanted to know why there isn’t an investigation into elementary and middle schools, where council members said students are often promoted to the next grade without mastering course work.

“There are so many red flags,” council member Trayon White Sr. (D-Ward 8) said. “What are we doing to make sure that this doesn’t happen again?”

Wilson said change is underway in the traditional public school system. He cited the Office of Integrity he launched earlier this week. The office will create a central place where teachers and families can express their concerns about school practices and have them addressed.

Wilson also said his office will more rigorously train teachers on city policies and will review all transcripts to ensure that graduating seniors are eligible to receive their diplomas.

Kang said the superintendent’s office will consider intervening if the school system does not implement widespread changes.

Wilson pushed back on some council members’ charges that the graduation scandal means the school system has made no progress in recent years.

“We have some significant challenges,” he said. “I can assure there has been real progress to acknowledge and celebrate.”