What makes someone smart? Is it something you're born with, an intelligence imprint in your genes? Does it depend on whether your parents read to you when you were 2? Are there those who simply have it and others who never will?

The answers depend on whom you ask. Indeed, the debate about just what intelligence is, how you measure it, who has it and what it gets you has raged -- and shaped public education -- for most of the past century.

The Bell Curve. The Seven Intelligences. Emotional Quotient. And now comes a new theory: the idea that smart is not something you are, it is something you can get if you work hard enough at it.

The theory is called "effort-based intelligence." It's an idea as old as Confucius, but it's just beginning to gain currency in U.S. education. The Montgomery County school system is one of the few in the country to embrace it wholeheartedly, using the approach to teach students at all grade levels.

"For years, people thought that intelligence is innate, fixed and determined," said Darlene Merry, Montgomery's associate superintendent for staff development. "What we are saying is that people can get smarter: that achievement is based on effective effort, that it's the responsibility of teachers to teach that effective effort, and it's up to children to do it."

In the effort-based system, children who don't understand lessons right away are considered not slow, but "not yet."

Instead of giving big red zeroes and moving on, teachers are encouraged to find what these children need to help them learn -- be it flashcards, a study buddy or a lesson in organizing notes. Assignments are redone and tests retaken until a concept is learned.

The idea is to help struggling children connect with their interest, spark their motivation and, through hard work, build confidence that they are capable of mastering challenging academic material. Teachers are taught to preview coming material in forums outside of class, to build the confidence of slower learners rather than place them in remedial courses.

"The goal is for the slower child to sit in the classroom and get it with everybody else, not two days or two months later," said Max Thompson of Learning Concepts Inc., a teacher-training company. He refined the idea of effort-based intelligence by studying "exemplary" schools with high poverty and high performance.

Some public schools in the District, as well as those in Detroit, Milwaukee and St. Louis, also have begun using the approach, and they report early signs of gains in student achievement. The mantra that teachers are taught to relay to students, through their words and actions, is: "This is serious. You can do it. I won't give up on you."

It all sounds so much like common sense. But proponents claim it is nothing less than radical. It is a new way of thinking that flies in the face of "The Bell Curve," the controversial book that argued that intelligence, as measured by IQ testing, is inherited and that some people -- particularly people of color -- have less of it. In other words, the achievement gap is preordained and there is little teachers can do to change it.

Bell Curve critics accused the authors of bending scientific studies to promote racist views of white superiority. But that line of thinking -- that intelligence is inherent and unchanging -- has colored the way schools are structured and children are taught -- and especially what teachers expect, often unconsciously, from their students.

"I've had children give up easily and tell me, 'I can't do this, Miss Johnson. I'm stupid.' Well, obviously, someone told them that," said Kurshanna Johnson, a fifth-grade teacher at Brown Station Elementary School in Gaithersburg. "A lot of times, teachers have been accustomed to seeing the same scenario with kids. You make assumptions. And you never give that child a chance."

Jeff Howard, a social psychologist who runs the Efficacy Institute in Massachusetts, pioneered the thinking behind the effort-based approach in the late 1960s while at Harvard University. For years, he pondered why the kids who were so quick-witted on the playground stumbled in the classroom. And he came to see a vicious circle.

"Adults decide which kids are smart and which kids are not, and they let the kids know," Howard said. "The kids who aren't considered very bright figure out it's silly to commit effort at something they're not going to get. When they stop working, they fail to build intelligence. When they fail to build intelligence, they fall behind. The adults say, 'See, I knew he wasn't very intelligent.' It's a self-fulfilling prophecy of a debilitating lack of intellectual growth."

Even scholars who hold other views say that anything that gets students working harder is constructive. But they dismiss effort-based teaching as yet another empty educational slogan.

"You could have tremendous motivation to be the best football player or French chef, but you have to have ability in those areas as well," said Joseph S. Renzulli, director of the National Research Center for the Gifted and Talented at the University of Connecticut.

Jonathan Saphier of Research for Better Teaching, who has been training teachers in Montgomery County, said the importance of defining intelligence didn't become pervasive in the United States until the early 1900s. Then, with masses of immigration, an industrializing economy and a new test to measure human Intelligence Quotient, it became imperative to sort people -- who was destined to run the factory and who to sweep its floors -- and to educate each person accordingly.

That created a system of tracking "bright" and "not so bright" children and steering them through decidedly different educational experiences, said Merry of Montgomery County. "We always used to believe that some kids got it and other kids didn't, and you just had to move on without them," she said. "We left those kids behind. It's been that way forever."

But then came the standards movement of the 1990s, which gave real impetus for school systems to find different ways to crack the code. And now No Child Left Behind, the new federal education law, has put public schools on notice that they will face consequences for failing to educate all children, not just the smart ones.

"The tenet of democracy is, no matter where you're born, you have an equal shot at the good life. That's something we have let slip," said Saphier, whose book "The Skillful Teacher" is the bible for training teachers to think that intelligence comes from effort, not from genetics. "It could be that there are, within our own society, class reasons for not doing that. If all of a sudden inner-city schools got very good, there would be a lot of competition for those seats in the freshman class at Harvard."

Gaithersburg fifth-grade teacher Kurshanna Johnson says it is too easy to doubt a student's ability. "I've had children give up easily and tell me, 'I can't do this, Miss Johnson. I'm stupid.' Well, obviously, someone told them that," she says.