Lucy Kneissler and Emma Maxtutis made their way to school the old-fashioned way - on foot.
The pair trailed their parents to Dallin Elementary School in Arlington, Mass., their conversation meandering with their small footsteps. They discussed what they might be for Halloween - Lucy a princess, Emma a bride - and their birthdays.
For the girls, the walk was mostly just a nice way to start the morning - although they were excited about special footprint stickers that awaited them at school in honor of International Walk to School Day.
But for their parents, the walk to school was part of a more complicated decision.
Walking to school, an activity long taken for granted, is gaining prominence once more. But parents are torn. While they want their children to get the exercise and fresh air, they also worry about their kids' safety. So parents in Arlington have banded together to form "Walking School Buses."
The popular concept places at least one parent in charge of collecting a gaggle of children, each from his or her home, guiding them on their morning trek, and depositing them safely at school.
"The police aren't there, traffic's speeding by at 40 miles per hour, and nobody's going to put their kids on the road," says Mark Fenton, host of the PBS series "America's Walking."
"So the idea was, walking school buses would allow parents to feel comfortable because their kid is walking with an adult."
Thirty years ago, more than 66 percent of students walked to school. Today, that number has dropped to just 13 percent, the Centers for Disease Control report. And as families struggle with overweight children - their number has tripled in the last 30 years - walking to school gets kids moving.
The walking bus Lucy and Emma "ride" is an informal version of those that have sprung up throughout Britain and Australia - also created in response to concerns about child safety.
The more structured models involve a "driver" who heads up a snaking line of "passengers," and a "conductor" who anchors the rear. There are designated kid "stops" and a fixed "route."
The walking bus's popularity has spread more slowly in the US than abroad. But recently, it has traveled to communities like Palo Alto, Calif., and Dallas.
The first US walking buses formed on the streets of Chicago in 1997. After a spate of school shootings, worried parents began plucking their children from neighborhood schools. To ensure that the kids could return safely, parents and educators volunteered to accompany them.
Today, the grass-roots effort has evolved into an organized program. And 90 percent of Chicago's 422,000 public schoolchildren walk to school.
The dangers facing students in Arlington, and suburban schools like it, are more likely to come in the form of speeding cars, sidewalks in ill repair, or lack of crossing guards. Six crossing guards once manned the intersections encircling Dallin. Now, a shrunken budget has left the school with just four. And Heather Thomas's sons must navigate an unprotected six-lane intersection.
"I just can't see letting them do it by themselves," says Ms. Thomas, who works as Dallin's coordinator for Safe Routes to School, a pedestrian advocacy program.
Another reason Thomas wants her kids - and others - out walking: Last year, the boys took two periods of gym each week. This year, there's just one - another casualty of budget cuts, says Dallin Principal Robert Lynch.
What has Thomas found to be the biggest challenge in organizing walking buses? The parents.
"New Englanders are so fiercely independent," she says. Which may be why more casual arrangements work best in Arlington. Parents can enjoy the security of knowing their kids will arrive safely at school, the convenience of sharing the responsibility for getting them there, and the flexibility of a walking bus that can be tailored to their schedules.
More than 50 percent of Dallin's 425 students walk to school, up from 35 percent when Safe Routes began five years ago. Mr. Fenton says the walking bus is just a start. It should be used as a tool for developing walkable communities.
"While you are doing it, aggressively survey the built environment to determine what you need to improve - permanently - so kids can walk all the time and you don't have to shepherd them every day."
But for now, Lucy and Emma are happy with their pedestrian bus. A week after the official Walk to School Day, they were pounding the pavement again. Once her shoelaces had been tied and retied, Emma was picked up by her pal, Lucy, along with Megan, Haley, and Lauren.
This day was different, though. The girls designated it "walk to school on your heels day" - a somewhat tricky exercise. But at least it kept them moving.