Kids' unstructured playtime faces tough competition from electronics, overscheduling, declining recess and increasing homework.

Yet research increasingly shows that active, open-ended play not only makes for happier, calmer kids, but it is also critical to their full development — intellectually, physically and emotionally.

When the Minnesota Children's Museum in St. Paul set out to renovate and expand, Barbara Hahn, the museum's vice president of learning innovation, wondered: "How do we create new exhibits to unleash the power of play?"

The answer was basic. Give kids wood to hammer and saw, fabric to sew and stitch, and structures to build and tear down. Don't tell them what to do or how to do it.

"We flipped the usual script and created experiences that will let play work its magic," says Hahn, the mastermind behind the museum's updated space and philosophy.

The $28 million makeover, unveiled June 7, increased visitor space 35 percent. It created 10 new exhibits and added a four-story climbing structure called the Scramble.

Visitors will find fewer exhibits that emphasize facts or learning. Instead, there will be more activities that allow children to put their imagination in the driver's seat. The Forces at Play exhibit's ball launcher activity, for instance, provides tubes, hoses and valves but lets kids figure out how to assemble their own launcher without a defined challenge or target.

The bigger hope is that the museum inspires families long after their visits.

"A two-hour visit to the museum is great," Hahn says, "but we want parents to appreciate the value of play, and give the time, space and freedom for it in other areas of their child's life."