More than half of the 408 U.S. National Park Service areas (national parks as well as historic sites, national monuments, preserves, and other significant places) are part of the Junior Ranger Program, which offers school-age kids the opportunity to learn about individual parks by filling out a short workbook or participating in an activity such as taking a hike with a park ranger. After completing the program, kids get a badge (or a pin or patch, depending on the park). For availability, check with the ranger station or visitor center when you arrive. Kids can also complete Junior Ranger activities online (www.nps.gov/kids/jrrangers.cfm).
In addition to the Junior Ranger Program, kids can find a variety of activities in the parks designed just for them. Some parks, such as Canyonlands, Grand Canyon, and Saguaro, loan "Discovery Packs," backpacks filled with kid-friendly tools like magnifying glasses. Call ahead for availability.
Many parks also have general-interest programs for kids. For example, Rocky Mountain National Park offers "Skins and Skulls," where visitors can touch a bear's fur and a marmot's skull, among other things. It's a safe way to get hands-on with wildlife.
When you're through with the organized activities and are ready to head off on your own, remember that kids often take a shorter view of things than adults do, meaning they may need to be reminded once in a while of why you're there and what lies ahead (especially if it’s a cool waterfall or swimming hole). Singing camp songs, playing games like I Spy, or staging scavenger hunts will help kids refocus if they get bored or whiny.