But when it comes to encouraging healthy habits, the nation's schools still aren't earning straight A's.
About 19 percent of schools served french fries to students in 2006, down from 40 percent six years earlier, according to the study by the Centers for Disease Control and Prevention.
The percentage of schools that sold cookies or other high-fat baked goods as part of a fundraiser dropped from 67 percent to 54 percent during the six-year period.
And in nearly half of schools, students can select bottled water instead of sugary drinks from school vending machines or snack bars, up from nearly a third of schools in 2000.
Public health officials are cautiously optimistic about the changes.
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"We're not satisfied. We still have a long, long way to go, but it is encouraging," said Howell Wechsler, director of the CDC's Division of Adolescent and School Health.
About 90 percent of districts require physical education in all schools. The figure has risen in recent years at the elementary-school level.
Still, it is rare for schools to provide daily physical education to kids in all grades.
About two-thirds of elementary schools provide daily recess to all students.
Students need daily exercise, said Jan Harp Domene, president of the national PTA. "Kids that learn this at an early age will practice this into adulthood," she said. "We are growing a whole generation of couch potatoes."
About one-third of U.S. children are overweight, and 17 percent are obese - figures that have been rising.
"We're really at the early phases of trying to counter what right now could be the most pervasive health problem that ever hit the United States - that is obesity in children," said Dr. David Appel, a pediatrician and the director of the Montefiore School Health Program, which provides medical services to school children in New York.
The survey found about a third of schools have a full-time nurse, a figure that has remained steady. About half of schools employ a part-time nurse.
Wechsler said getting more full-time nurses in schools is advisable, so they can keep an eye on injuries and wounds and help ensure good sanitary practices are in place.
That is important in light of recent cases of staph infections in schools. One Virginia student hospitalized with an antibiotic-resistant staph infection died this week.
The federal study shows states are increasingly requiring middle- and high-schools to teach sex-education and pregnancy prevention.
HIV counseling, testing and referral services also are up in middle and high schools.
And bullying prevention programs are more common. The percentage of elementary and middle schools that participated in programs to prevent bullying increased from 63 percent to 77 percent. The CDC doesn't have that trend data for high schools.
The use of security or surveillance equipment also is on the rise.
About two-thirds of schools have a ban on tobacco use at school and at off-campus, school-sponsored events. That's an increase from roughly half of all schools in 2000, but it's short of the 100 percent goal set by public health officials.
Wechsler said it's hypocritical for educators to tell kids not to smoke, while allowing cigarettes at school-sponsored events.