Earlier this year, Nadia Lopez was ready to quit her job at Mott Hall Bridges Academy. Lopez founded the public middle school in 2010, hoping to provide educational stability to students in Brownsville, Brooklyn—the poorest neighborhood in New York City. Four years later, though, she worried her work wasn't influencing the community.

Then Vidal Chastanet, an eighth-grader at Mott Hall, was featured on the Humans of New York photo blog, where he praised Lopez as the most influential person in his life. "When we get in trouble, she doesn't suspend us," he said. "She calls us to her office and explains to us how society was built down around us." The post, which immediately vent viral on Facebook, was shared more than 145,000 times. Three days later, Stanton and Lopez started a fundraising campaign to send Mott Hall students to visit Harvard. The campaign attracted significant attention online, raising more than $1.4 million in just three weeks.

In February, The Atlantic’s video team spent a day at Mott Hall to learn how Lopez responded to the attention, and more important, to understand why she is such a successful principal. As Lopez explains it, her hands-on approach is a big reason why Mott Hall has become such a safe haven in Brownsville. “In this building, my kids are going to feel like they’re successful,” she said.