"This is a historic moment in our nation," Williams told the students. "Did you know that there has never been any school with the same mission as this school?"
He then told his personal story of being born to an unwed mother and of being lucky to have been adopted by a schoolteacher father and a mother who was a secretary.
Even after he was adopted, he said, "I had an aunt who described me as a throwaway baby.
"But don't let other people define you like my aunt tried to define me," Williams urged.
He said he worked hard in school. He said he even failed at his first attempt in college - when he flunked out of a military college. But he said he learned from his failure and returned to college, graduating from Penn State before going on to law school.
He urged the students that if they worked hard, they could accomplish anything they wanted to do in life.
"If I can do it, all of you can do it," Williams told the teenagers. "All of you can be great!"
"Amen?" Williams then called out. "Amen!" a few of the students in the front row responded.
Agnes Butler, the foster mother of six boys, has two sons enrolled in Arise. She said she hoped the school would provide the support her sons need.
"It can be hard for foster children in a regular school because other kids can be cruel," Butler said. "What kids need is a sense of belonging."
She said the fact that all of the students are in foster care will help them learn without worrying about being different in a regular school where most of the children are living with their biological parents.
Jill Welsh-Davis, president of Arise Charter school, is also deputy director of program development of the Greater Philadelphia Urban Affairs Coalition, which founded the school.
It was Welsh-Davis who more than five years ago approached her boss, Sharmain Turner-Matlock, and suggested that the coalition begin a charter school for students in foster care.
Welsh-Davis said that in her work with the coalition, she had noticed there was a core group of teenagers who were always absent from programs aimed at helping them either return to school or go into job training, after they had dropped out.
She soon learned that most of the "always absent" teenagers had family problems and were constantly changing foster homes.
"Many of these kids have been traumatized; many have gone from home to home. As they were placed in different homes, they changed schools. There was no continuity about school."
Yesterday, Welsh-Davis asked students to raise their hands if they had been to more than one high school. About 30 hands went up. She then continued until two students said they had been to seven different high schools.
"Well as long as you choose, you don't ever have to go to another high school," Welsh-Davis said. "You've got a home here at Arise Academy."