The magnet schools are working.

Gauging how good a school is can be tricky. Gauging how hard it's trying is easier: all you have to do is look at the exhibits in the hallways. At Capitol Heights Elementary School, part of the ambitious new Prince George's County school desegregation plan, the hallway walls bear hundreds of mimeographed contracts, each signed by parents who pledge to check their child's homework nightly, "because I am vitally interested in the best elementary school education for my child, and I want to help in every possible way."

Increased parental support is just one facet of the sweeping reform effort that Prince George's County instituted last fall. The plan uses a web of different "magnet" programs -- some accelerated, some specializing in math and science, some offering extended day care near parents' work places -- to draw white families into predominantly black schools.

At the two magnet schools in Capitol Heights, an inside- the-Beltway district that has gone from mostly white to mostly black over the past 20 years, the scheme is working: test scores are up, waiting lists long, and the schools fairly breathe with reformist energy.

But not just because of the plan's elaborate technical details. School systems don't magically improve themselves simply by shifting students around, as some reformers (such as supporters of the U.S. Department of Education's voucher proposal) seem to hope. Rather, the Prince George's plan promises to work because Superintendent John A. Murphy has used desegregation as a spur to make the schools a focus of attention, enthusiasm and money -- to make teachers, principals and students alike feel they are part of a grand experiment.

"I was honored to take on the TAG program -- it's almost a once-in-a-lifetime experience for any principal," says Dr. Linda Duffy, principal of the Walker Mill Middle School. "P.G. County is in a position to create something wonderful."

Both Capitol Heights Elementary and the nearby Walker Mill Middle School host the most controversial types of magnet programs, those for children identified by county testing as "talented and gifted," or TAG. The pitfalls are both educational and racial: the programs bring predominantly white, certifiedly "gifted" children into the mostly black schools and then offer them an enriched academic program in separate classes. The obvious questions are whether the (excellent) quality of the TAG programs will spill over into improvement of the whole school, and whether the mix achieved truly constitutes desegregation.

The Prince George's plan doesn't skirt these issues. It mixes the kids as much as possible throughout the day, in joint home rooms, gym, art and music. It gives everybody access to the new labs and computers. It also offers students in the regular (still mostly black) classes extra opportunities and encouragement to "cross over" to TAG if they qualify. Still, it is a tricky proposition, and since September the schools have been host to a constant parade of parents, bureaucrats, journalists and other worried observers.

"I told my teachers, 'It'll be a fishbowl, and if you want to bail out, do it now,' Velma Butler, the principal of Capitol Heights Elementary. "We didn't lose one." The challenge was considerable: 130 new kids, eight new (white) teachers, a revolution in schedules and techniques. It helped that Butler, like all the magnet principals, got to do her own hiring of the newcomers -- a piece of autonomy that would seem to be obvious good management but is, in fact, something public-school principals nationwide have been fruitlessly demanding for years.

It also helped that the feared racial tensions barely materialized. Butler, who is black and has taught at interracial schools all over the world, said the only surface sign of stress was "a lot of stomachaches." And now, asked whether the black kids and the white kids go their separate ways, black sixth-grader Rocky Brooks looks perplexed: "Course not. That wouldn't be right."

Things were slightly less sunny at Walker Mill Middle, where half the faculty left and the school got a new principal, vice principal, 20 new teachers and 220 new students all in a rush. "We came on kind of strong," principal Duffy admits. Walker Mill saw little racial strife, but for a while there was much use of, and ensuing violence over, the term "nerds."

The main, unavoidable stress of the TAG magnet programs falls on the TAG kids themselves. It isn't easy to leave a familiar school where you were known as smart and plunge pell-mell into a strange new group where everyone else is just as high-powered. Those who have always found school easy often come into the TAG program with inadequate self-discipline or poor study habits. The problem becomes more severe the further along in school they are; it is worse at the middle than the elementary school, and will be tougher still at the projected TAG high schools.

Still, despite these hurdles, Walker Mill too emits redoubled energy and excitement. Duffy's talk of a "rebirth" is echoed from an unlikely quarter. Sophia McGary and Trina Martin, two black eighth-graders hanging out in the cafeteria, are rowdy, stylishly dressed, mischievous; neither has any interest whatever in the TAG academic program. But they emphatically agree the school has improved -- not just because of the new intramurals, which they love, but because of the heightened attention and firm new discipline.

"No drugs," says McGary, "no drugs at all, and" -- slapping her hip pocket with cheerful but disconcerting emphasis -- "just you try to get in that front door with any kind of weapon." Martin chimes in: "Vice Principal (Bruce) Speight is strict, but what I like is that if I'm up from the table, he'll look all the way across the room and say, 'Where's Trina? She here today?'

Such dependable attention, the sense of someone keeping an eye out, is crucial for kids at any academic level. They get more of it when teachers and principals have been inspired to spend extra time and energy, to work as a team and feel that the eyes of the county are upon them. That teacher energy is what is turning the Prince George's County magnet schools around. It is what must be maintained -- by traditional means, such as salary hikes, as well as by attention and novelty -- to continue this progress after the shine has worn off the new science labs.