As a black child in the segregated South, Lisa Delpit recalls teachers extolling her to “act your age, not your race.”

A MacArthur “Genius Grant” winner and former Georgia State University professor, Delpit maintains that racism, while not as overt, still taints America’s classrooms in subtle yet damaging ways.

“It exists as much in the North as the South,” Delpit said in a telephone interview from her home in Louisiana. “The country believes at its core that black people are less than — it is a mindset that the entire society has.”

Delpit expands that theme in “Multiplication is for White People,” a follow-up to her bestselling book “Other People’s Children.” She opens her new book by debunking the notion that low-income black children are born at a disadvantage, noting that there is no achievement gap at birth and that black infants lead in many developmental benchmarks.

She argues that the academic struggles of black students — despite reforms created to help them, including the No Child Left Behind Act — are due in part to the perception that these children cannot excel because the obstacles in their lives cannot be overcome.

“The question is how do you convince others that a people who have been marginalized are as competent and capable as everyone else,” she says. “My bias is when you believe it, you will see it.”

And Delpit says she has seen it in schools where poor, minority students excel despite what many contend are insurmountable odds.

“In Baton Rouge, where I am now, there are two schools a mile apart serving the same population of low-income, African-American children. In one school, the children have won state recognition for high scores and high performance,” says Delpit. “In the other, there is absolute failure.”

If the children share the same backgrounds, what accounts for the difference? Delpit says we ignore the simplest explanation: Many poor African-American children are not being taught. They attend desultory schools where worksheets and seat work are standard, where teachers seldom leave their own chairs to teach and where few probing questions are ever asked.

“It has to be what goes on in that school,” says Delpit. “If it were just poverty, if it were just the community, if it were just the parents, then no one could do anything.

“But if there is one school of extremely poor children where the students are performing extremely well, it removes the basis for saying it can’t happen.”

The key, says Delpit, is teaching. “Good teaching is desirable, but any teaching is preferable to classrooms where teachers have abdicated the role completely. And good teaching is miraculous.”

Good teaching requires connecting to students and their worlds, something that she said is being overlooked in the celebration of rescue efforts such as Teach for America. While acknowledging the dedication of many Teach for America recruits, Delpit has concerns about the reactions of these young people when they encounter challenges.

“One of the things we know is that black and brown children don’t just learn from a teacher, they learn for a teacher. If they feel connected to a teacher, they are much more likely to learn,” she says.

Freshly minted Ivy League graduates dropping down into poor communities like missionaries in a foreign land often lack that vital bond, says Delpit.

“Without knowing the community, without knowing the kids, without knowing the culture, you are destined to have great challenges in teaching,” Delpit says. “What happens is that many of the TFA folks start to blame the parents and the community because, if they are not successful, it cannot be them — they have been told they are the best and the brightest. It must be these families and these communities.”

But can children only learn from people like themselves?

No, but children must see some teachers who look like them, share their backgrounds and know their culture, Delpit says. Otherwise, “They are going to come to believe that academic success doesn’t look like them and isn’t something they should be aspiring toward or working toward. ”

“Children succeed when schools focus on extraordinary instruction,” says Delpit, who fears the testing frenzy set off by No Child Left Behind undermines such instruction.

“We are making school less interesting and expecting students to learn more and it just doesn’t work that way,” she says. “There is little tolerance for difference, for creativity or for challenge.”