HARLEM – The late-day sky was spitting snow. Inside the classroom, tiny black children, younger than kindergarten, sat in a circle, legs folded “criss-cross apple sauce” beneath them. Soon, they would begin their French lesson, but first there was a ritual chant.

“There is a girl in our class, and her name is Khadija,” they began, voices rising in little-kid enthusiasm, hands clapping in time. Khadija got up, moved to the center of the circle and began jumping with all her heart. “Jump, jump, Khadija,” they sang. “We’re glad you’re here today.” Around the room they went until each child had had a turn in the center of the circle.

In the hours I recently spent touring the Harlem Children’s Zone, a 97-square block network of schools, social services and teen outreach programs, I saw many affecting sights. But for some reason, the most affecting was this portrait of sweet innocence, flourishing in one of the nation’s poorest places.

I came here seeking “What Works.” That’s a series of columns I’ve started to highlight difference makers, people who are finding solutions to the dysfunctions that affect black children disproportionately. (To learn more: www.leonardpittsjr.com.)

The HCZ is the brainchild of Geoffrey Canada, a 55-year-old New Yorker who believes you cannot effectively educate a child when his world is falling down around him, when he is hungry, sick, fatherless, homeless, hopeless. Canada’s solution: Fix it all. Simultaneously.

He told me, “We think you start this at birth. And you continue it until kids graduate from college.”

Canada’s other key innovation: Think big. What good is it to save one child and send him into a neighborhood where every other child is failing? “Well, after a while, it has an impact on your child. That kid either never goes outside again or they learn to adjust in that environment.”

He calls that a “negative contagion.” And, he asked, “What if we could create a “positive contagious effect?” Meaning, what if we could send that child out into a peer group of other children who were also doing well? As he sees it, it’s not enough to save a child here and there. We have to save the “children.”

So overall, the Zone serves more than 9,000 kids. Its students have smaller classes, a longer school day and a longer school year than their peers. Their teachers are paid more and given more classroom freedom, but are also held more accountable. After school, the kids take karate and yoga classes, get tutored, paint murals, practice plays, dance, write.

Family in crisis? There is counseling in the Zone.

Child sick? There is health care in the Zone.

Family being evicted? There is emergency aid in the Zone.

Child malnourished? Thirty pounds of farm-fresh produce costs $5 in the Zone.

The price tag: $50 million a year, two-thirds of it from private donations. To those who question that investment, Canada points out that the state spends about $60,000 a year to jail one inmate. “Someone’s yelling at me because I’m spending $3,500 a year on ‘Alfred.’ ‘Alfred’ is 8. OK, Alfred turns 18. No one thinks anything about locking him up for 10 years at $60,000 a year.”

The HCZ model is being studied and implemented from Liberty City in Miami to San Francisco to Israel to the United Kingdom. While its kids test higher than their peers, the HCZ says it won’t be possible to truly quantify the program’s success until the first group of kids to be in the program from birth graduates from high school, still a few years off.

Until then, I’m persuaded that success can be inferred anecdotally. It’s in the surprisingly capable second-grade renderings of Van Gogh’s “Sunflowers” that adorn a principal’s wall. It’s in the high school hands shooting up in response to a question about Newton’s Second Law. And it’s in the eager leaps of those little ones at the center of the circle.

“Jump, jump, Khadija. We’re glad you’re here today.”

Leonard Pitts Jr. is a columnist for The Miami Herald. His e-mail address is: lpitts@miamiherald.com.