You can't teach history — not American history, not Philadelphia history — without talking about race.

It would do an injustice to the subject matter and, more important, the students, said H. Richard Milner IV, the urban education chair at the University of Pittsburgh and director of its Center for Urban Education.

Dozens of teachers gathered Thursday morning at the National Constitution Center nodded, snapped, and clapped along as Milner spoke. He urged them to remember context as they taught their students about Octavius Valentine Catto, an often-forgotten teacher and civil rights activist who fought to desegregate Philadelphia's horse-drawn streetcars and bring African Americans the right to vote.

"We can't teach Catto if we don't teach race," Milner said during his keynote address at Thursday's teacher-development workshop, emphasizing one of 10 reminders he laid out for the educators: "Race still matters."

Catto was murdered in 1871, at just 32 years old. He sought to protect fellow African Americans who were trying to exercise their right to vote, which had just been ratified by the states the year before. But his name had been largely missing from the modern discussion of civil rights, organizers have said.

As he has been brought back into popular consciousness — a sculpture is set to be placed next month on the southern apron of City Hall — the School District of Philadelphia, the Catto Memorial Fund, and the National Archives partnered for Thursday's event, the first in a yearlong series aimed at helping teachers include Catto in their curricula, the educational counterpart to the physical memorial.

The statue is the first of a named African American on public ground in the city. The work, titled Quest for Parity, will feature the 12-foot-tall bronze statue, a stainless-steel ballot box, and five granite pillars symbolizing streetcars.

"The Catto story is the national story. It is part of the story of our Constitution. It is the story of how ordinary citizens work, some every day, to make the Constitution live," said V. Chapman Smith, an organizer of Thursday's event who works at the National Archives and who is on the board of the Catto Memorial Fund.

The fund has raised enough money for the sculpture and is continuing a fund-raising campaign for educational programming. Among the materials teachers received was an educational magazine, Octavius V. Catto: Remembering a Forgotten Hero, describing Catto's life.

Mayor Kenney, delivering opening remarks, said he had not heard of Catto until he was older than 40. "The contributions of people of color in the United States, and the world, were systematically ripped out of the pages of our history books," said Kenney, who argued that a full understanding of history is important for all students, including white ones.

The mayor joked about the controversial statue of former Mayor Frank Rizzo — "We have a lot of statue problems in Philadelphia" — and also decried the white supremacist marches and violence in Charlottesville, Va., this month.

"Think about a period of time in our country, in 2017, when neo-Nazis are marching through a college campus in Virginia with torches," he said, describing it as one of the frightening things he has seen since childhood. "The way we fight back is by knowledge and information and the way we teach our kids what really happened in America."

Milner, too, connected history to current events, drawing lines between the life of Catto and those of Philadelphia students today, pointing to racial disparities throughout the school system: suspension rates, expulsion rates, the reasons for discipline. Black students make up 52.7 percent of the school district, he said, but 81.5 percent of out-of-school suspensions.

"When you look at these data, we know that something's going on," Milner said. "If you're not doing race work, as educators, you're not doing the work."

Milner urged teachers to be aware of their students' lives and understand that the classroom cannot be isolated. All teachers can do the work of promoting racial literacy and helping all students, he said, regardless of teacher background and identity.

It takes effort, he said, but it's necessary. And it might ensure that fewer Cattos get forgotten in the future.