On the first day of classes for Washington area public schools, it was clear that spray painters had left their mark this summer in the hallways, stairwells and bathrooms of Nicholas Orem Middle School.

Rarely has the Hyattsville school looked so good.

The falcons, serpents and other stenciled designs adorning the campus were not the handiwork of gang taggers. Nor were the multihued murals at the front doors, nor the life-size plywood silhouettes of students tacked onto the walls in nearly every corridor.

The people responsible for remaking the school grounds: more than 100 students in a summer school project guided by Latino youth advocates and a University of Maryland community initiative. They even planted a vegetable and herb garden in a once-desolate courtyard.

"These hallways were really dark," David Aparicio, an eighth-grader, said as he showed off a corner splashed with eye-catching triangles. "We decided to use funky colors, lime green and light orange, to lighten it up."

Yesterday, the 14-year-old was back in class along with an estimated 139,000 other students in Prince George's County public schools. Schools open today in Calvert County and Thursday in Frederick County. In much of Maryland -- including Anne Arundel, Charles, Howard, Montgomery and St. Mary's counties -- public schools will open Monday. So will schools in the District and in Virginia's Loudoun, Clarke, Spotsylvania and Fauquier counties. Most Northern Virginia public schools will open after Labor Day.

Prince George's moved up its start date last year to pack more instruction before winter break and before state standardized tests. The tradeoff: More of August's dog days are now school days. With temperatures yesterday pushing into the high 80s, air conditioners strained to chill some schools. At Orem Middle, which lacks central air, students sweated in hallways and in gymnasium assemblies; some teachers were raising their voices in classrooms to speak over the rumbling din of window air conditioners.

Orem Middle, serving a predominantly black and Hispanic population in a neighborhood next to the Prince George's Plaza shopping center, is one of many schools across the region in which educators seek to tamp down the influence of gangs and ramp up the academic performance of low-achieving minority students.

Echoing several other students, parents, teachers and administrators interviewed there, David, the eighth-grader, said a school once known for large numbers of student fights and suspensions had calmed within the past year. "Gangs are out of here," he said.

School officials said they were on alert for gang tensions following heavily publicized stabbings this month at a Montgomery summer school and shopping center and in the Prince George's community of Langley Park.

"We're very concerned about it," said William Ritter, a regional assistant superintendent for the Prince George's school system. "No matter what happens in the county, this is where the kids are all day, so it's going to bleed into the school."

Kenneth Calvin, a former Army intelligence officer in his second year as Orem Middle principal, said he has taken steps to quell student violence. He said the school once averaged about 400 suspensions and 150 fights a year. Last year, he said, there were 56 suspensions and 11 fights. "We cut all that craziness out," he said.

Calvin, who describes the school's previous atmosphere as resembling "a prison" or "a dungeon," said administrators and teachers now focus more on talking with students and less on punishing them. There are no mandatory uniforms. There are no buzzers or bells at the end of class. Teachers line up students and walk them to lunch or to class. Calvin also works to boost school morale by handing out freeze pops or other treats to students every Friday after a fight-free week.

Parents said they are impressed. "I've heard good things," said Kelvin Rodriguez, who has a son and daughter at the school. "They're upbeat. It used to be known as one of the worst schools for gangs, fights, expulsions. But that's changed."

Said history teacher James R. Boyd: "There are gangs. They're here. But they're not evident in the building. Here we are Nicholas Orem -- that's the gang."

Now that he has essentially reclaimed the campus, Calvin said, he will try to improve its academic standing. State reading scores at Orem sagged or stagnated last school year, though math scores rose a bit. More than half of the students tested in both subjects failed to show proficiency. Those results mirror statewide trends among schools in high-poverty areas. Improving literacy rates is a crucial challenge for middle-school educators as they seek to get early adolescents ready for the rigors of high school.

State Superintendent of Schools Nancy S. Grasmick, in an appearance yesterday at Glenarden Woods Elementary School in Prince George's, said she would push this year to publicize the rising stakes of state testing. Incoming ninth-graders, she said, will for the first time be required to pass state exams in various academic subjects to receive a diploma. "It's absolutely critical that we see systemic high school reform, with quality instructors," Grasmick said.

Opening day for Prince George's schools was about logistics -- getting 1,300 buses to run on time, getting 95,000 students to learn the bus stops, opening new and rebuilt campuses in Suitland, Capitol Heights, Bowie and Bladensburg. In a tight market for qualified teachers, some principals also were hiring faculty up to the last possible hour.

Calvin interviewed 12 candidates yesterday from 6 to 8 a.m. to fill four vacancies in a teaching staff of nearly 60. After welcoming 750-plus students who arrived for classes by 9:30 a.m., he then addressed about 50 parents, urging them to monitor their children's homework and get them to school. "You need to make sure they're here," he said. "Everybody understand: We can't educate the children if they're not in school."

Nicholas Orem Middle School students walk by a mural completed during the summer, part of an effort to brighten the Hyattsville campus.

Orem Middle School Principal Kenneth Calvin helps guide students such as seventh-grader David Hidalgo, right, to their homerooms.

David Aparicio, right, laughs at a joke made by his teacher during class with fellow eighth-grader Christopher Navarrete. David says violence at Orem Middle has dropped.