Four years after Mark Zuckerberg made his $100 million donation to help the Newark, New Jersey, school system, most of the money is gone and critics say the city has not turned into the "symbol of educational excellence" he had hoped for.
That's because a silver bullet, no matter how large and well-intentioned it is, won't magically change years of social and economic inequality, Randi Weingarten, president of the American Federation of Teachers, told CNBC's "Power Lunch" on Friday.
"The work we're involved in is not a silver bullet kind of work. You have to engage the community, you have to have a shared sense of what you need to do and then you have to do it," she said.
One of the criticisms of Newark's school reform has been the lack of input from the community, according to The New Yorker, which examined the city's efforts.
Read MoreRobin Hood donors raise $60 million
Ken Berger, CEO of Charity Navigator, said while Zuckerberg had good intentions, his generous gift was not very well-thought-out.
"We see this very often, that people start from the heart ... but then when it comes to the question of using the community, engaging the community, sometimes that gets lost and there's a top-down approach that occurs where there's a disconnect with the realities on the ground," he told "Power Lunch."
"Here we had a foundation with only millionaires on it," he added.
Facebook declined CNBC's request for an interview with Mark Zuckerberg.
The New Yorker reported that between 2010 and 2012, more than $20 million of Zuckerberg's gift and matching donations went to "consulting firms with various specialties: public relations, human resources, communications, data analysis, teacher evaluation." Consultants were paid $1,000 a day.
"Everybody's getting paid, but Raheem still can't read," Vivian Cox Fraser, president of the Urban League of Essex County in New Jersey, told the magazine.
Read MoreMystery $13 billion philanthropists revealed
The Foundation for Newark's Future, tasked with distributing Zuckerberg's donation and matching gifts, said it has invested more than $82 million in initiatives.
"We have dramatically increased access to school options for Newark families, provided grants directly to teachers at 37 schools, given 300,000 books to Newark students through the My Very Own Library program, and just recently, we committed to a $1 million initiative to improve early childhood education in Newark," the foundation said in a statement to CNBC.
It said it also provided "critical funding" for a new teacher contract.
Read More Learning to give away money the Buffett way
Weingarten, who worked on the teacher contract in Newark, said there were some good legacy things that came out of the donation. However, the philanthropic agenda didn't match other things that were going on in the city, like the state cutting $56 million in school aid, she said.
"We want business to be involved in schools," she said. "The lesson here is we need the engagement of the whole community."
—By CNBC's Michelle Fox and Kerima Greene.