In Harlem, school is in session 24/7. Children never stop learning. And Geoffrey Canada learned more on the street than in school.

“The first rules I learned on Union Avenue stayed with me for all of my youth,” Canada wrote. “They were simple and straightforward. Don't cry. Don't act afraid. Don't tell your mother. Take it like a man. Don't let no one take your manhood." Such lessons, Canada also learned, spun the cycle of violence he summed up in his book — Fist, Stick, Knife, Gun.

Geoffrey Canada was lucky. Sent by his single mother to live with grandparents on Long Island, he won a scholarship to Bowdoin College, then Harvard. But returning to Harlem, he found the same cycle. When he started teaching there in the 1980s, male life expectancy was lower than in Bangladesh. Canada decided to do something about it.

Three decades later, a new generation of Harlem kids is learning new rules. Each morning at two Promise Academies, kids recite a credo:

We will go to college.

We will succeed.

This is our promise.

This is our creed.

Oprah Winfrey called Geoffrey Canada an angel. TIME Magazine called him “one of the most influential people in the world.” But all he did was come to Harlem with streetsmart charisma and one radical idea.

Why should social programs form a tattered patchwork? One agency working on education, one on health, one for parents, one for teens. . . Why not start ONE organization doing “whatever it takes” to help kids succeed. And why just a dozen kids? Or even a hundred?

“We’re not interested in saving a hundred kids,” Canada says. “Even three hundred kids. Even a thousand kids to me is not going to do it. We want to be able to talk about how you save kids by the tens of thousands, because that’s how we’re losing them.”

Since the mid-1990s, the Harlem Children’s Zone has helped parents and kids save themselves. Grown from a single block to the present 97 blocks, the HCZ now nurtures 13,500 students and their parents. Students are divided into those living outside “the Zone,” who attend a Promise Academy, and those within the Zone who also use its wealth of programs. These include:

— Baby College, teaching new parents better skills, notably how to discipline without hitting;

— The Three-Year-Old Journey (for parents of toddlers);

— All-day pre-kindergarten (Harlem Gems);

— After school programs for 2,000 “Peacemakers”;

— Health clinics and community centers;

— Counseling on getting into college and staying through graduation.

What began with an idea grew into a promise. At the zone’s first school lottery in 2004, parents and kids packed into an auditorium at P.S. 242. Canada called their attention, then made his promise.

“We are calling our school Promise Academy because we are making a promise to all of our parents. If your child is in our school, we will guarantee that child succeeds. There will be no excuses. We’re not going to say, ’The child failed because they came from a home with only one parent.’ We’re not going to say. . . If your child gets into our school, that child is going to succeed.”

One hundred names were called. (The first is now at SUNY Buffalo, the second at Ithaca College.) Another 111 went on a waiting list. Canada vowed to expand the Zone and has since filled two Promise Academies. Each has classes from 8-4, nearly year-round! In 2017, the Promise Academy college acceptance rate was... 100 percent. Promise kept.

Beyond the streets of Harlem, the Zone was profiled on Oprah, on “60 Minutes,” and elsewhere. But Canada’s biggest fans were in the White House. In 2007, Barack Obama praised the Harlem Children’s Zone and promised to replicate it if elected.

Under Obama, the Department of Education modeled its new Promise Neighborhoods on the Harlem Children’s Zone. Along with inner cities, Promise Neighborhoods can now be found in East Lubbock, Texas, Berea, Kentucky, Meriden, Connecticut, Macon, Georgia. . . Obama’s successor proposed slashing the program, but the most recent budget included a slight increase.

But do they work? Education professors have tested and re-tested. Along with soaring college attendance, Princeton found that “girls at Promise demonstrated a 59% lower teen pregnancy rate and the incarceration rate among boys had been lowered by essentially 100%.” Test scores in math erased the usual racial gap.

Critics charge that the Zone siphons students into the controversial charter system. And with its wide publicity and generous funding, the Harlem Children’s Zone is a tough act to replicate. But recalling the street lessons he learned to challenge, here Geoffrey Canada’s answer:

Canada, now 69, stepped down as HCZ director in 2014. He now devotes his remarkable energy to speaking, fund raising, and work with agencies run by other angels. But his vision remains in the Zone.

“Over the past five years,” he says, “I’ve met several presidents, several Secretaries of Education. . . And there is no plan. If you want to save your children, you’re going to have to do it yourself. It’s just us.”

HARLEM CHILDREN'S ZONE -- 13,000 KIDS, 97 BLOCKS, AND "WHATEVER IT TAKES"