When my dad was growing up in the 1950s, he says he had only sticks and rocks and maybe a dead rat to play with. None of the bright plastic junk we spoiled children of the 1970s and '80s had in abundance. Boy, did we ever feel lucky. Turns out, dad probably had the advantage, thanks to all that experience with makeshift toys.

A growing body of evidence finds that children of all ages who play outside and play with natural, found materials — such as water, rocks and dirt — have better physical and mental health, greater social resilience, and more creativity than their couch-surfing counterparts. In 2005, Richard Louv's "Last Child in the Woods: Saving Our Children From Nature Deficit Disorder" detailed a growing body of research tying rising rates of obesity, depression, and attention-deficit disorder to children's limited access to nature. Newer studies out of Britain, Switzerland and Finland throw even more weight behind Louv's argument.

"Outdoor play gives you multiple bangs for your buck," said Cathy Jordan, associate professor of pediatrics at the University of Minnesota, and a member of the Minnesota Children and Nature Connection, an organization that promotes outdoor play and natural environments for children. "When kids have exposure to nature, they reap physical and emotional benefits, improve their attention and focus, and learn social skills through playing in a calming environment that has relatively little cost or risk."

It doesn't take much. A child will enjoy going down a slide only so many times, whereas a patch of sand or dirt, some rocks and water, plus a few good logs for climbing, can provide hours of imaginative play. In 2008, the National Toy Hall of Fame inducted "The Stick" into its lineup of all-time best toys, calling sticks "the original building blocks for creative play" and noting that "sticks can turn into swords, magic wands, majorette batons, fishing poles and light sabers."

Now playground designers are catching on. The functional steel pipe playground of my youth gradually gave way to a series of so-called improvements in the form of wooden play structures (which waned due to rampant splinters and rotting), brightly colored plastic habitrails (you crawl through — and then what?) and high-tech gyroscopic playgrounds (offering three minutes of play, tops — and then vertigo). Today's hottest playgrounds appeal to all ages by going back to the basics — the very basics.

Natural play spaces are designated patches of land devoid of any fancy playground equipment. Instead, kids are outfitted with dirt, sand, water, logs and sticks. In the 10 years since my eldest son was born, we've seen new nature play areas pop up at schools and parks across the Twin Cities. They're a big hit with users (cities and parks like them, too, since the projects are more budget-friendly than building traditional playgrounds). The natural play yard outside the Eco Experience building at the Minnesota State Fair kept my kids busier than any other activity this year. Hoping to encourage a more freestyle form of play, administrators at my kids' school in the east metro opted to install wood chips and rocks rather than a conventional playground. And here's the latest development in the local natural-play trend: When Dakota County opened its new Whitetail Woods Regional Park two weekends ago, the Fawn Crossing natural play space was packed with hundreds of busy, dirty, happily absorbed kids.

"We can send kids into the woods to play, and that can be great, but when you intentionally construct a natural play space, you create a breadth of experience that you wouldn't find in a natural environment," said Jordan. "That can mean design for parents, in terms of sightlines and seating, and opportunities for multiple ages to use materials that you might not naturally find all in that place."

Jordan added that designed natural play spaces can ease parental fears about injury, noting that traditional playgrounds, with their elevated structures, have more risks than ground-based nature play. For instance, the fixed nature of playground equipment means kids can bore quickly and start climbing all over the exterior of play structures. A well-equipped natural play area provides them with safer options.

"The key is to let kids design their own play," said Jordan. "Adults tend to have more limited ideas about how to play. For instance, in one place, adults constructed a play area with a straw-bale maze. Kids came in and deconstructed the maze. Adults reconstructed it. Kids took it apart again, and built their own thing. Adults thought a maze was fun, but kids thought it was more fun to play with the bales. Finally, the adults realized that they had to listen to the kids and let them use the materials the way they wanted to. Kids just needed to have the materials, and a place to use them."

Amy Goetzman is a Twin Cities writer.