"And that's something that Arlene gave to the city of Philadelphia - to dare to dream," he said.
Johnson and others said Ackerman believed that all children, even the neediest, could achieve, and stood up for them as if they were her own. She was dynamic, outspoken and never apologized for who she was, speakers said.
Sandra Dungee Glenn, former chairwoman of the School Reform Commission, recalled that it took her six weeks in 2008 to persuade Ackerman, who had been superintendent in Washington, D.C., and San Francisco, to come to Philadelphia.
"She took her warrior heart and brought it here," Dungee Glenn said. "She would say, 'Sandra, I'm only here for the babies.' "
Ackerman told her, " 'I'm not going to send any child to a school that is not good enough for my sons.'
"She was a warrior . . . she was out there fighting," said Dungee Glenn. "I don't know that we did all we could to protect her."
Ackerman, who was bashed for some fiscal decisions and what her critics called an overbearing management style, was ousted in 2011 and given a $905,000 severance.
Her advocates said that she was a tireless educator who mentored aspiring teachers and built strong relationships with parents.
Sylvia Simms, a grandmother and former bus aide who now sits on the School Reform Commission, started to tear up when she remembered that parents lined up at roundtable discussions to talk with Ackerman.
"She stayed and heard from the very last parent," Simms said.
"She gave us hope, love and wisdom, and opened doors to see what a quality education for our children would look like," she said.
Music legend Kenny Gamble described Ackerman as a "real friend," and "like a sister."
"What Arlene Ackerman knew was, the only way to solve our problems in our community is through education," Gamble said.
"It's very simple. When you know better, you do better."
Johnson said that Ackerman often stood up in church - symbolic of how she lived her life.
"She kept getting up day after day," he said, his voice getting louder with each word.
And when she got beaten down, she said to herself, " 'Still, I'll rise,' " he bellowed.
"Thank God she came to Philadelphia. She kept on rising," he yelled, reaching a crescendo.
"Keep on rising!"
Johnson spread his arms and lifted them to the ceiling.
"Arlene, I'll see you next time.
"Keep on rising."
On Twitter: @barbaralaker