More than 120 primary schools in Gloucestershire are taking part in the national Walk to School Week campaign.
The event aims to encourage parents to stop using their cars when getting their children to and from school.
For this year's theme, pupils are asked to become "sound detectives", exploring their environment through noise.
County councillor Stan Waddington said: "The exercise you get is a great way to start the day and there are extra benefits for our environment as well."
Councillor Joan Nash added: "These days, it's perfectly natural that outside factors persuade parents not to allow their children to walk to school on their own.
"But this sort of event, when hundreds of schoolchildren all over the county take part, is a great opportunity for them not only to join in and see what they're missing, but perhaps think about changing their routine".