Seth Andrew, Democracy Prep's founder and superintendent, speaks at a fundraiser for Harlem Prep, a new school run by his network.

Who’s more important to New York City than Jeremy Lin, the city’s sudden basketball sensation? According to Mayor Michael Bloomberg, one answer is charter school operator Seth Andrew, who runs the Democracy Prep network of schools.

Bloomberg made the comparison at an Upper East Side fundraiser for Andrew’s latest project: turning around one of the city’s worst elementary schools, Harlem Day Charter School, which his network adopted last year in the state’s first—and so far only—charter school takeover.

In 2011, Harlem Day was arguably the worst elementary school in the city, Bloomberg and Andrew told their audience as servers floated around the darkened, East 60th Street restaurant offering dumplings and sushi rolls. Last spring, the State University of New York charter school authorizer granted Democracy Prep permission to take over Harlem Day, now called Harlem Prep.

The Wall Street Journal reported last June that 40 percent of students were held back, including two-thirds of fifth-graders. Teachers at the benefit put that number even higher, with some saying they thought as many as 70 percent of students had repeated a grade after Democracy Prep took over.

State education officials have said it’s too soon to tell whether the experiment will pay off. But Bloomberg said the school “really is bound to become one of the best schools in the city for kindergarten through fifth grade.”

The challenge before Andrew, he added, “Was seeing the beauty in someone else’s vision, and transforming it into something that touches peoples’ lives for the better.”

Most of Harlem Prep’s teachers left the party early to prepare for the 7:15 a.m. start to their workday. But the three I spoke to told me that the strides students are already making halfway through the year have everything to do with the network’s culture of high academic expectations and citizenship.

“We’ve done a lot of work on how kids feel about themselves in the last few months. I think you can see the difference in the way they carry themselves when they walk around the halls,” said Danielle Liebling, a third grade teacher. “It doesn’t feel like the same school I interviewed at at all.”

The teachers, all former Teach for America members who have worked in public schools in New York City and Atlanta, rattled off a list of Harlem Prep students who said they “hated school” last September and loathed reading exercises. Now, some of them have become top students, Roberto de León, a fifth grade teacher, said.

But he noted that it has been an added challenge to teach students who have been held back a year.

“I have 5th graders, they should be 10 years old. But I have 10 11 and 12 [year olds],” de León said. “That’s important to me when I think about how they should be in 6th or 7th grade. What do 7th graders do, what do they like, how do they think?”

Tameka Royal, a fourth grade teacher, said she has encouraged the students to think of themselves as “active citizens” by volunteering on election day and discussing current events. She said she has the same expectations for every student in her class, regardless of their age.

“I didn’t want to know how many students were held back so I didn’t look at the list when I started,” she said. “Because I know that you are going to be on grade level when you leave. It doesn’t matter, you’re going to get the where you need to be by the end of the year and make tremendous gains.”

Earlier this year, the take-over of Harlem Day inspired the principal of Peninsula Preparatory Academy, a charter school in Far Rockaway that the city plans to close, to ask the city to allow the school to be taken over too. At the time, Andrew lamented that there is no system in place to overhaul low-performing charter schools rather than close them outright.

The audience at Tuesday night’s fundraiser snapped their fingers to applaud Andrew’s speech—mimicking a technique some teachers use as a substitute for clapping—as Andrew encouraged them to donate money to help the network grow to accommodate the thousands of students on his schools’ waiting lists.

“We can prove the naysayers wrong because this is not a selective group of kids. These are the exact same families with the exact same poverty, same challenges in their day-to-day lives,” Andrew told the crowd, nodding to the teachers who stood off to the side wearing the network’s signature yellow hats. “Our teachers are working every day to transform the school.”