Megan Schroeder rides her bike or walks to school to do her part to help the planet.

She also likes the incentives that her school, Bear Creek Elementary, uses to reward kids who ditch mom or dad's car in favor of biking or walking.

"You get treats, too — usually some kind of food. I won a bike at the awards ceremony," said Megan, 8, of Boulder, Colo. "Since I like animals, I want to save the environment."

Across the country, schools are encouraging families to forgo their cars to promote healthy habits, relieve traffic congestion around school buildings and reduce auto emissions. Students who live too far to walk or bike are asked to form car pools, use public transportation or walk part of the way.

Prizes for walking or biking to school range from bottles of water to digital cameras, bike bells to bicycles. Many schools and community groups are funding the programs with grants from the national Safe Routes to School program, administered by the Federal Highway Administration. The FHA has funded programs in 40 states.

"It's unrealistic to just say, 'Go out there and walk,' " said Darleen Reveille, a public health nurse who works for the city of Garfield, N.J.

She has worked with the Garfield Public Schools and the local YMCA to develop walk-to-school programs that appeal to parents and children.

Some parents worry about their children's safety, bad weather and heavy book bags. Many find it easier to drop their kids off at school on the way to work.

"I knew there was going to be some resistance from parents," said Sal LaSpisa, school-age childcare director at the Garfield YMCA. "They were apprehensive."

But it usually didn't take them long to appreciate the value of walking, he said. "They saw not only how great it is, but how simple it is."

Walking provides an opportunity to exercise and socialize before school, proponents say, and can have a long-term impact on health. Students who exercise regularly are less likely to become obese or diabetic. And exercise in the morning can improve readiness to learn, Reveille said.

The Federal Highway Administration wants to get the word out that walking to school is not a dangerous proposition, said Katy Jones, manager of the Safe Routes to School program in Chapel Hill, N.C.

A student has a greater chance of being struck by lightning than getting hit by a car, she said.

The FHA works on finding safe walking or biking routes and funding sidewalks. The program received $612 million to spend on the effort between 2005 and 2009.

One of the best ways to reach parents is through children, Jones said.

"Kids asking their parents, 'Please, will you walk me to school?' can be an effective strategy," she said.

The program at Bear Creek Elementary in Boulder is "kid-generated," said parent volunteer Jim Kornish.

"They're the ones saying, 'Let's leave early and walk,' " said Kornish, who organized a weekly walking route that involved meeting kids at designated spots along the way.

Since the school started promoting walking and biking, there's been less traffic around the school, he said.

Megan Schroeder's father, Paul, is happy to leave his car at home and pedal 3.5 miles to school with her.

"It saves money on gas," he said. "In a tiny way, it helps the environment."

And that makes Megan happy.

"I don't want more pollution because pollution can actually kill animals and also make the hole in the ozone bigger.

Additional information about walking and bicycling to school is posted online at National Center for Safe Routes to School' s Web site, www.saferoutesinfo.org.