From my trip to Yellowstone in 2006.

Every Kid in a Park is a National Park Foundation initiative intended to get students and their families to explore national parks, forests, and wildlife refuges in the United States. The program provides fourth grade students in U.S. schools with a free pass to all national parks (parents and siblings also get in for free). Parents and students can register for passes individually. Teachers can click here to get passes for all of their fourth grade students.

Applications for Education
As long time readers of this blog know, I am a big advocate for getting kids outdoors to exercise, explore, and learn. Every Kid in a Park provides an excellent opportunity to introduce students to the joys of the great outdoors. To help teachers get the most out of a park visit with students, Every Kid in a Park offers some suggested field trip activities in every state in the union.

H/T to LifeHacker.