There is no boombox at lunch today, so the break dancers at Montgomery Blair High School are without their usual soundtrack. The lack of music doesn't bother Izal Saddler, an 18-year-old from Silver Spring. He lowers the volume on the Michael Jackson CD in his Discman and turns to his friend Jesse Galef.

"You wanna just break anyway?" Izal asks.

Jesse smiles and shrugs. Of course he wants to.

Short and wiry with fair white skin, Jesse drops to the ground, moving his hands and feet as if he were on hot coals rather than the grimy school floor. Izal, on the other hand, needs his space. The 6-foot-4-inch African American senior nearly slams into the book bags lined against the wall. Students edge past as he lies on his back to do a windmill, whirling his long legs in the air.

Conversation is minimal, unless it's about breaking. These guys have little else in common. They aren't in any of the same classes. Jesse, a bespectacled senior from Silver Spring, is in Blair's elite magnet program, while Izal takes a mix of honors and regular courses. Jesse is a Monty Python fan, while Izal prefers Japanese anime. They rarely hang out outside of school, but during lunchtime, they are tight.

Now Izal and Jesse are beginning to sweat.

"Windmills are psychotic," Izal says as he gets up off the floor. Then he's back down again and attempts to hover over the ground with only one hand for support. He crumples into a heap and groans.

Enter Erik Li, a lanky Asian sophomore who puts Izal and Jesse to shame with his spinning handsprings. From somewhere outside their circle, a voice calls out jokingly: "You got served!"

The guys just keep dancing. Everyone knows the enclave inside the front doors of the school is their territory. Behind them stretches the school's main hallway, a multicultural crossroads known as Blair Boulevard. It's lined with students of every conceivable background scarfing down their lunches wherever they can find a space to sit. Hundreds more students are crammed into the cafeteria. Ethiopian students claim the same two round tables every day. Hispanic teens gossip in Spanish by the window, while Asian girls in Abercrombie wander past, and pint-size white freshman boys huddle together. Waiting in line for french fries can take all period.

This is life at Montgomery County's largest high school, where, as one teacher puts it, "everybody is a minority." Blair's 3,300 students are divided among blacks (32 percent), whites (28 percent), Hispanics of either race (26 percent) and Asians (14 percent). One-third are current or former students in the English Speakers of Other Languages program; they speak 50 different languages and come from more than 80 countries.

These are kids two or three generations removed from the desegregation struggles set in motion by the Supreme Court's landmark decision in Brown v. Board of Education. Their educational experience has been transformed not only by integration, but by immigration -- a wave of diversity that hasn't reached all schools. In fact, many schools in the Washington area and across the country are actually resegregating, studies show, not growing more diverse. That makes Blair and its teenagers all the more compelling. Walking Blair's hallways, sitting in its classrooms and talking to its students offer a glimpse into a truly post-Brown world, a place where race sometimes matters a great deal and sometimes doesn't matter at all.

Some of the old divisions still exist. Blair's two most touted academic tracks -- the science, mathematics and computer science magnet program, and the communication arts program -- are overwhelmingly white and Asian. Regular classes, meanwhile, are filled mainly with black and Hispanic students. In remedial classes for kids struggling to read on an elementary school level, there often are no white kids at all.

The academic achievement gap is accompanied by another gap that is not as easily defined. Many of Blair's cliques break down along racial lines, and so do many of its extracurricular activities. The ultimate Frisbee team, for example, is almost entirely white. The tennis and volleyball teams are mostly Asian. The step team is dominated by African American performers.

The break dancers, though, are different. The dozen or so regulars who belong to Blair's break-dancing club come from every corner of the school and represent almost every demographic. There's Josh Gist, a sophomore who is half black and half white, half Christian and half Jewish. There's Doula Favian Makao-Scheid, a part-Nigerian, part-German and part-Irish senior who dreams of going to culinary school. And there's Mai Tran, a recent Vietnamese immigrant who is not sure how old she is because her birth certificate has never been found.

"Breaking at our school has nothing to do with anything else, really," says Izal, who has been with the group for two years. "We kinda all meld together."

The bell rings. Lunch period is over. As students flood Blair Boulevard, the break dancers grab their book bags from a pile in the corner and head to class without saying goodbye. No need. They may be headed in different directions, but they'll see one another tomorrow.

JESSE GALEF IS BRANCHING OUT. This semester only two of his classes are magnet courses. The rest are electives, Advanced Placement and honors classes. It's a welcome change of pace after spending most of his four years at Blair cloistered in the magnet program. Until this year, even his non-magnet classes were often filled with magnet kids because of the way the schedule worked.

"I've enjoyed being at Blair," says Jesse, who just turned 18, "but . . . I didn't meet as many people as I had hoped. I was seeing the same faces in all my classes."

That racial/ethnic divide permeates the school and is reflected in its test scores. Last year white students scored an average of 1295 out of a possible 1600 on the SAT. Asian students ranked next with an average of 1221. Hispanics scored an average 911, while black students posted an average of 902. The Maryland High School Assessments produced a similar racial divide.

Asian and white students dominate Blair's magnet program. Of the program's 400 students, 202 are Asian, 190 are white, six are African American and two are Hispanic. Of the 283 students in the communication arts program, 230 are white, 31 are black, 19 are Asian and three are Hispanic.

The same racial breakdowns apply to many of Blair's Advanced Placement courses, including Jesse's AP comparative government class. Of the 31 students who signed up for the class, 17 are white, 10 are Asian, two are Middle Eastern and two are African American. There's not a single Hispanic student sitting in the room.

On a February morning at the start of the semester, the students review the American political spectrum: liberal vs. conservative, libertarian vs. authoritarian. Jesse doesn't take notes. He knows all this already.

A fast talker and even faster thinker, he wants to study psychology and computer science in college and has applied to a bunch of hard-to-get-into schools, including Brown, Brandeis, Carnegie-Mellon and the University of Maryland. He knows a lot of break dancers at College Park.

By the end of the period, the students are discussing the meaning of democracy. Do too many voices stymie progress or "does diversity make democracy more necessary?" asks teacher David Swaney.

The students are split. On one hand, there have been dictatorships like Nazi Germany, where Jews, Gypsies and other minorities were first silenced, then segregated and finally exterminated by the millions. On the other hand, many countries are plagued by small, warring factions that make government by consensus nearly impossible. Just look at Nigeria, a student says. Thousands have been killed since the country ended 15 years of military rule in 1999.

"If there's too much diversity," he argues, "it doesn't work."

WHEN PHILIP GAINOUS BECAME PRINCIPAL of Montgomery Blair High School in 1984, he faced a dilemma. In the three decades since Montgomery County had integrated Blair's all-white hallways, the school had become a victim of white flight. Its students were almost entirely black and Hispanic, putting Blair in danger of violating a county policy, since repealed, that capped the percentage of minorities at any school. The county would have to bus students in from other parts of the county if school leaders could not come up with an alternative plan.

Thus, the magnet program was born in 1985. The idea was to draw the best and brightest math and science students from across the county to offset Blair's increasingly urban population. But in reality, Gainous says, the program had one real objective.

"It wasn't to have a diverse program," he says flatly. "It was to get as many white kids down in this school as I could."

It worked. The magnet program, along with the communication arts program created three years later, ensured that Blair would attract a steady stream of high-performing white and Asian students.

The magnet program is open to students from across the county. But to get in, they must pass a series of tests measuring their math and verbal skills, achievement and critical-thinking abilities. Only 100 students are selected each year. Last year nearly 700 applied.

Requirements for the communication arts program, which the students refer to as CAP, are less stringent. The program is open to students who live within Blair's district and have at least a B in English and social studies honors courses. Once in, they must maintain a 2.75 grade-point average.

Critics say that the elite programs have created schools within the school. The magnet program, in particular, has drawn both high praise and harsh condemnation. No other high school in the Montgomery system offers such rigorous science courses, from quantum physics to thermodynamics, or has such state-of-the-art labs. Two of the region's five finalists for this year's prestigious, $100,000 Intel Science Talent Search scholarship attend Blair.

Most of the magnet classes are on the third floor of the sprawling brick building at Route 29 and University Boulevard in Silver Spring. Magnet students and CAP students follow a separate schedule from everyone else. While the school day for most students ends at 2:10 p.m., magnet students must stay for an extra period of class that lasts until 3 p.m.

Gainous acknowledges that the school has a frustratingly long way to go to close the racial achievement gap. Yet the 61-year-old African American, who attended a segregated school growing up in Northeast Washington, takes pride in the progress that has been made at Blair. When he walks the hallways, he sees communication arts students tutoring immigrant kids, and students of all backgrounds and academic abilities using the library.

This year, all freshmen were required for the first time to enroll in a class that helps ease the transition from middle to high school. Before, that curriculum was offered only to magnet and communication arts students. Gainous says the school is trying to recruit more black and Hispanic students into the magnet program by encouraging them to take algebra in middle school, a prerequisite for acceptance. It is also looking at test scores of minority students to see if they belong in more challenging classes.

"On the one hand, it's really exciting . . . seeing how all these kids from all over the world are able to assimilate together and work together and understand and appreciate their differences," Gainous says. At the same time, teaching kids with such a wide range of backgrounds is "more difficult than if you had a homogeneous group of students."

"That's what makes this school real. We represent the world."

JOSH GIST IS SURROUNDED by strangers in health class. He was in the communication arts program until this semester. But then he got a C in journalism, which brought down his GPA. He was put into regular classes, like this one. Now his whole world has changed.

Health teacher Rich Porac has ordered the students to pair up and interview each other to help everyone get acquainted. One person has to talk for three minutes uninterrupted while the other takes notes. Then they switch. The students groan. Three minutes is a long time. Mr. Porac is unmoved.

Josh turns to his neighbor, one of the few people he recognizes, and starts talking.

My name is Josh. I'm 15, and I'll be 16 in 28 -- no, 26 -- days. My favorite color is orange. I love dogs and cats. My pet fish died. My shoes are blue, and I like to dance. I have a learner's permit. I'm an ex-CAPpie. We got a new house yesterday, and we move in late March. I haven't seen it yet, but I hope it's not in Rockville. I have 10 fingers and toes. My dad is bald. I have 62 cousins on his side, so there are a lot of relatives I haven't met. I am currently single.

What Josh doesn't mention is that his bald father is also black and Christian, while his mother is white and Jewish. Almost no one can tell he's not white. Josh is tiny and compact, with light skin, heavy eyebrows and thick brown hair. He generally doesn't like to make an issue of his background, though one time he did bring his family tree to school to prove to a disbelieving friend that he is biracial.

Once the interviews are done, Mr. Porac makes all of the students read their reports aloud. "You might be surprised to see how many connections you have with people you didn't even know," he says.

He starts at the back of the classroom. There's a student who has a dog named Pickle and says his friends have been in jail. Another boy is Guatemalan, likes cars, broke his arm while riding his bike and wants to move to Canada. There's a 15-year-old who describes himself as Persian. He likes rugby, plays the guitar and mandolin, wants to join the military, and his favorite book is Dante's Divine Comedy. Then there's a girl from El Salvador who says she is still a virgin. She has a tattoo, wants to get her nose pierced and believes in safe sex or no sex. Everyone likes rapper Jay-Z and hip-hop boy band B2K. The class is divided, however, over which is better: cats or dogs.

These stories are impossible to discern by scanning the faces in the classroom. In fact, it's difficult even to tell what race some students are, much less presume to identify some of their complex ethnic heritages. One student in Mr. Porac's class is part Vietnamese, part German and part Irish. Another is part Jamaican, part African American and part white.

And then there's Alastair Chuck-a-Sang, a senior who ticks off all the ethnicities in his family tree during an English class one afternoon: African American, Chinese, East Indian, Italian, English and South American Indian.

His friend Alexis Austin is quick to correct any mistaken impression that he's African American. "You think I'm black?" asks Alexis, a senior who is wearing a blue sports jersey and has coffee-colored skin and a short Afro puff. He pauses for effect. "I'm Spanish," he finally says. He sticks out his arm to show off a beaded bracelet with the name of his native country woven into it. "P-A-N-A-M-A," he spells out with pride.

THIS IS WHERE IT GETS COMPLICATED. Life at Blair is not divided into black and white, as it was 50 years ago when Brown was handed down.

Many students at Blair maintain that they simply don't think about race. Prejudice is out; multiculturalism is in -- just look at any Gap ad. J.Lo, Beyonce and Jessica Simpson are all equally adored. The kids say they form friendships that cross previously impermeable color boundaries without a second thought, or even a first thought.

"I notice people's race," Jesse says. "I just don't care very much."

Izal says he doesn't either. He applied for the magnet program but didn't get in. He blames it on lack of sleep the night before he took the entrance exam, not on his race. To make up for it, Izal has taken seven science classes -- the norm is three or four -- and spends part of the school day on an engineering internship. He wants to major in premed at Montgomery College.

Izal's teachers are always pestering him to join the communication arts program, but he turns them down. He just doesn't like English, he says. The small number of African Americans in the program doesn't bother him, though he thinks that has made some of his black friends reluctant to try it.

"The few who got in felt outcast and like they didn't belong," he says. "It's kinda sad that they think that way, but, at the same time, we live in a time when you don't have to think that way."

Izal revels in the multicultural camaraderie at Blair. Some of his Hispanic friends have joined the school's Cambodian Club because they like the food and the dances. He jokes with them about their taco-making skills, and they demand to know why he's not a better break dancer.

"When we start teaching about the civil rights movement, there's just this complete, like, 'No way!' This disbelief that [segregation] ever happened or went on," says teacher Hunter Hogewood, who runs the school's alternative reading program.

But underneath the friendly jabs and easy socializing, there are still some lines that cannot be crossed and some walls that have yet to be broken down.

Like when Eric Glover, a sophomore in the communication arts program, laughs with his mostly white friends about being the group's Token Black Guy whose role is to say slangy things like, "That is whack!" But when he hangs out with black friends outside of school, he worries that they think he's "too soft." He often feels suspended between two worlds -- a result of being in so many classes with white students, he says.

Or when, despite English teacher Vickie Adamson's best efforts to handpick a class that includes seniors from different races and academic levels for her American studies elective course, the students still sit in predictable clusters: magnet and CAP kids on one side, regular students on the other. She has switched to assigned seating.

Then there's the black student in Josh's health class. One minute he's joking around with a guy from El Salvador sitting behind him, and the next minute he's angrily whispering: "Don't call me a nigger . . . I'm so serious, man." And then comes the response: "Don't call me a spic."

Norma Menjivar had played softball her whole life in El Salvador. But she found trying out for Blair's junior varsity team as a freshman daunting from the moment she approached her gym teacher about it. "He said, 'Do you play softball?' " she wrote in an article about the experience for Silver International, the ESOL department newspaper, before graduating last year.

" 'Yes, I have been playing softball since I was a little kid,' I said. I think he did not believe me because he looked at me as if he was thinking, 'I do not know if she is telling the truth.' "

For many immigrant students like Norma, life is all about race and ethnicity: learning a new language, adjusting to a new country, trying to fit in. At the softball tryouts, she was the only Latina out of about 50 girls. The other students had their own bats and gloves, she wrote. She brought nothing. Norma, who ended up making the team, went home and cried.

IZAL HAS SEEN MANY THINGS in life that he calls "unusual."

Walking around Rockville, Izal notices women moving away from him and giving him "funky looks." Sometimes he'll mess with them, he says, either adopting his most thugged-out walk or by addressing them with the utmost politeness.

Most unusual was when Izal was at the 7-Eleven up the street from his house and the clerk, an immigrant from Africa, accused him of stealing. The clerk even called the cops to investigate. Izal had to empty his pockets to prove he was innocent.

For the most part, life inside Blair is different. Teachers and students say there is little overt racial animosity, though the school expelled several students a few months ago for fighting. School officials were worried that some of the kids may have had gang ties.

Blair can be seen as both the new demographic standard and the exception to the rule. This year, for the first time, Montgomery County's graduating class will not be majority white. And yet most schools across the country are actually resegregating. Fifty years after Brown, about 69 percent of black students in the United States attend schools in which racial minorities are a majority. About 35 percent are in schools that are more than 90 percent minority, according to the Harvard University Civil Rights Project. The percentage of Latino students in similar situations is not as high, the report says, but is increasing as well.

"I never actually realized how diverse Blair was until I visited other schools," Jesse says. "It was a major change to look around and realize: Everybody at this school is white."

IT'S A FRIDAY AFTERNOON, and Blair Boulevard is nearly empty. Most of the students have left school already, eager to take on the weekend. That leaves the break dancers with free rein.

The dirty version of the rap song "Roll Out" by Ludacris is playing full blast on the boombox. A regional break-dancing battle against students from Seneca Valley High School is coming up, and the Blair kids need practice. About a dozen of them form a circle. Jesse, Josh and Izal are here. They take turns dancing in the center -- spinning on their backs, spinning on their heads, spinning on one hand.

"Now it's hot!" Josh calls out to one guy whose legs are bending and popping like rubber. "That's the footwork I'm talking about!"

A small crowd of after-school stragglers forms around them: skater kids, ESOL students, girls in tight jeans clutching their binders and giggling. One shy Asian boy is even taping them with his tiny digital video camera.

Some of the break dancers' faces are turning red. Jesse has ditched his glasses. Then, there's a collective: Whoa!

Greg Donaldson, a tall, lean white sophomore, has just executed an airflare. He'd been in a handstand, then pushed himself off the floor, using his legs to spin himself around and wind up back in a handstand. So maybe Greg didn't quite land the rotation, but he was really close. No one else in school can do an airflare.

The shy Asian boy has caught the moment on video. He smiles broadly and waves everyone over to watch. They barely know him, but everyone crushes around him, straining to see Greg's miraculous move in instant replay.

For a moment at least, nothing else matters.

Ylan Q. Mui covers education for the Metro section of The Post. To see a video about Blair's break dancers, visit www.washingtonpost.com/education.