From the site:
The National Park Service’s on-line Junior Ranger program for kids of all ages. If you love your National Parks, Monuments and Historic Sites, this site is for you. Play more than 50 games and learn about your National Parks.
Share park stories and pictures with other WebRangers around the world in My Community. Now there are 83,259 registered WebRangers; 3,538 have earned WebRangers patches by completing all of the activities.