Books have been written about our nature-deprived children. There are organizations dedicated to helping kids learn how to play outdoors. And then there is the wonder of Mother Nature-the country's national parks-where a kid really can be a kid and a family can get back to nature.

Sunday is Earth Day, which marks the first day of a week of free entry into all of our national parks.

The closest national park-and one of the country's best-is just an hour away at Indians Dunes National Lakeshore in northwest Indiana.

If you've never been, you might want to wait until the warm winds blow again, but even a chilly spring day or a snowy winter one are better when they're spent walking the sand dunes along lake Michigan's southern shore. To get a taste of what you'll see when your there, check out this video of Indiana Dunes from the national Parks Foundation.

Whether you get to the Dunes this week, or have to wait until summer vacation, find some way to give your kids some quality time outdoors.

Cindy Richards is the editor for TravelingMom.com, which sponsors a weekly Twitter party on Monday nights at 8 pm CST. The topic for the April 23 party: national parks. Follow the hashtag #TMOM to join the conversation. And follow Cindy @CindyRichards.

Cindy Richards is the mom of two who gets her muse from traveling the world, usually with kids in tow. She also writes for TravelingMom.com, where she also serves as editor.

See more of Cindy's stories here.

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