D.C. Public Schools Chancellor Antwan Wilson acknowledged Friday that the school system graduates a high number of chronically absent students, a practice that "doesn't align" with city policy.

But Wilson, appearing before the D.C. Council, also sought to defend the system, saying that students who graduate have earned their diplomas — even amid attendance concerns.

"I believe that our students earned their diplomas by reaching a level of mastery deemed appropriate by our teachers," Wilson testified.

D.C. Council member David Grosso (I-At Large) called a marathon, eight-hour hearing to investigate the state of high school graduation in the nation's capital amid allegations that Ballou High School in Southeast improperly graduated seniors who were chronically absent and didn't grasp basic reading skills.

An article published last month by WAMU and NPR reported that Ballou awarded diplomas to seniors who did not meet graduation requirements and that administrators pressured teachers to pass students. The school system and the Office of the State Superintendent of Education are conducting investigations, and the chancellor said he would take appropriate action once the probes are concluded.

D.C. council members said they do not believe that attendance and grading issues are isolated to Ballou, and they pledged to determine how widespread they are. One teacher who testified before the council said she thought Ballou was being used as a "scapegoat" for broader, systemic issues.

Council members grilled Wilson and other school officials about attendance and graduation policies, and questioned why there was not more oversight of the credit recovery program — an initiative that allows students to retake a class they previously failed.

Council Chairman Phil Mendelson (D) said the school system was cheating students by graduating them without meeting city requirements.

"We have cheated the students who were promoted, ultimately graduated, but do not qualify," Mendelson said. "And we are cheating the students who graduated — properly — because the value of their diploma has been degraded."

D.C. policy states that students should fail a class if they are absent for more than 30 classes in a school year. Wilson testified that about half of students who graduated from Ballou last year missed more than 30 days of at least one class that was required to graduate. The chancellor, who took over the D.C. school system in February, said chronic absenteeism is more pervasive in D.C. public schools than in other urban systems where he has worked.

Still, the chancellor, teachers and students who testified Friday conveyed a more complicated portrait of Ballou than the dysfunctional image portrayed in the media report. They said the predominantly black and low-income school is being unfairly maligned. Students said they are often absent because they are responsible for taking siblings and other young family members to school. They said that they are on track to go to college and that their teachers have prepared them to succeed.

Students said teachers become involved in their lives and work with them to ensure that they learn material and graduate, despite potentially high absentee rates. And they credited the leadership of Ballou Principal Yetunde Reeves with improving academics and the school's culture. Reeves was reassigned from her post pending the investigation, though Wilson said she could return to the school if the investigation finds she did nothing wrong.

"Ballou has provided me with a sense of love outside of my household," said Ballou junior Charles Thornton. "For once in my life, I just feel like I have love and care from a school that I attend."

Wilson, teachers and students criticized what they dubbed the "80/20" rule — a city attendance regulation that says students who miss 20 percent of the day are considered absent for the entire day. Students said their truancy records can be misleading because they often miss only one period, not all of their classes.

In an interview after his testimony, Wilson would not say whether he thought students who missed more than 30 days of a class should have been allowed to graduate.

"I believe that educators did what they needed to do based on the circumstances that they are in," Wilson said, adding that administrators must make sure teachers are aware of policies and follow protocol if they think they need to change a student's grade.