Give a girl a pedometer, and she walks faster.
That's what happened to seventh grader Rachel Held, when she received her small step-counting device.
"When I first got it, I wanted to run up and down the stairs to show I was not a couch potato," she said.
Held and about 85 other girls at Wilson K-8 School are participating in a nationwide study that could change the way schools in America teach physical education to girls their age.
The Trial of Activity for Adolescent Girls study, sponsored by the National Institutes of Health, will identify ways to entice adolescent girls to live active lives.
Teen-age girls are half as likely to get regular exercise as teen-age boys, according to a 1997 study by the Centers for Disease Control and Prevention. About 41 percent of 12th grade girls exercise regularly, down from 61 percent during ninth grade.
"I tell my fifth graders, you're really active now, but you're going to see a decline," said Katherine Franklin, a physical education teacher at the school.
The trend might have something to do with schools' emphasis on competitive sports over individual activities, the study said.
As part of the TAAG study, Wilson K-8 is offering students non-competitive after-school activities ranging from hip-hop dance to hiking to taekwondo.
"You're going to always have kids doing after-school sports," Franklin said. "What about the kids who are most likely going to get on the bus and go home to watch TV and eat bonbons?"
Wilson K-8 is one of three Tucson schools participating in the $30 million study. It was chosen randomly from Arizona schools that applied to participate and met the study's criteria. Three other Tucson schools are serving as control groups.
The University of Arizona is one of several field centers nationwide coordinating the study. It is providing instructional workshops to participating physical education teachers.
Wilson K-8's role in the study began last fall, when about 85 sixth-grade girls at the school wore monitors for a week to provide baseline data about their activity levels.
Now in seventh grade, the girls will spend this year and next focusing on their activity levels during physical education and health classes.
"I tell them kids their age should be taking 11,000 steps a day," said Kathryn Flemming, a health teacher at the school.
The students' trusty pedometers, which they wear during physical education and sometimes all week as homework, let them know how many steps they have to go.
Props supplied by grant money, including portable boom boxes and giant fitness balls, make the steps more fun.
Boys are not excluded from the school's revised physical education program - they just won't provide data for the study.
All seventh-grade students are keeping track of their activity for four straight days, without wearing the devices that do the tracking for them.
Later, they will wear the devices for four days to see if their perceptions of their activity levels are correct.
Part of their physical education grade will be to increase the activity in their lifestyle.
"They might find they have to wake up an hour earlier," Franklin said.
Eventually, the girls will develop their own personalized fitness calendars with activities that appeal to them, rather than activities prescribed by schools.
"In the past, unless you could run a mile or do this many sit-ups, you weren't physically fit," said Judith LeWinter, the assistant principal.
At the end of eighth grade, the study participants will wear their activity monitors again for a week to provide data for the TAAG study about how their activity levels changed.
Franklin, who has taught second- and third-graders as well as adolescents, said she notices a definite decline in physical activity with the older girls.
The second and third graders are not at all intimidated by exercise, she said.
"They're pure energy," she said. "They don't care how they look."
But the girls start behaving different than boys in fourth and fifth grade, she said.
"They don't want to stick out and be a star on the team."
That's when the seperation begins, she said.
In sixth or seventh grade, their self-consciousness is at an all-time high.
"A girl makes a mistake and it's a big deal to her," she said.
But the opportunities for exercise are so much more varied than just competitive sports, which is one lesson this study is aimed at imparting on girls.
"By the time you're 30 years old, about one percent of the population is playing team sports," Franklin said.