The National Park Service is marking its hundredth birthday with a special gift to kids. In a bid to get more students and families outdoors, the “Every Kid in a Park” initiative is providing free entrance passes to every fourth grader in the country throughout the 2015-2016 school year.

Secretary of the Interior Sally Jewell considers the initiative an investment in the next generation of environmental stewards. “We want to make sure that every American has the opportunity to develop a lifelong connection to our nation’s land, water and wildlife.”

From historic sites to wildlife viewing, the national park system holds endless possibilities for hands-on learning. Not sure where to start? Here are just a few of our favorite outdoor classrooms—all places we’ve helped protect with support from people like you.

You can learn more about the initiative—or get a park pass for your fourth-grader—at everykidinapark.gov. See you out there!