Don’t expect directions on how to build the Ping-Pong ball launcher or advice on how to scrub the wacky vehicle at the pretend carwash.

The new Forces at Play exhibit debuting this week at the Minnesota Children’s Museum offers plenty of creative fodder, but visitors won’t find explicit challenges or instructions on how to experience it. Instead, the setting is meant to encourage open-ended learning and play, said Nichole Polifka, the museum’s director of learning and impact.

“It’s the first exhibit of an entirely new approach to the museum,” she said.

That philosophy has guided the nearly $30 million renovation and expansion at the museum, which opened the first of 10 new exhibits Wednesday. The project has attracted a diverse pool of donors, including $14 million from the state, $1 million from the city of St. Paul and about $14.5 million from private foundations and corporations, including 3M.

By next spring, the museum will have gained about 35 percent more space, adding new galleries, a four-story climbing structure called The Scramble and a cafe. Visitors have until Dec. 4 to explore the Forces at Play exhibit before the museum closes for construction until early April.

Some parents like Krista Dahn, of Hastings, say they plan to use the museum’s pop-up play space at the Mall of America while the flagship building is closed. Dahn brings her three children to the St. Paul location about once a month in the summer. Her daughter, Lizzie, especially enjoys the trips, she said.

The carwash is part of a Children’s Museum exhibit, called Forces at Play, that invites visitors to test out various displays that pose challenges in science, technology and engineering, without directions.

“Lizzie is my little scientist — she loves to figure things out,” Dahn said during a recent visit.

At the Forces at Play exhibit, museum officials are counting on that childlike curiosity to steer families through its new 3M Gallery. Intuitive cues will guide visitors through each science activity, which all draw inspiration from air and water.

“There’s so much power in figuring it out for yourself,” said Dianne Krizan, museum president.

Mike Tindall of Shoreview agreed as he explored the exhibit with his children Wednesday morning.“It gives [kids] more freedom to explore and also learn about things like gears, pressure and air flow,” he said.

The exhibit’s ball launcher activity, for instance, provides tubes, hoses and valves but lets families assemble their own launcher without a defined challenge or target. Similarly, the car wash station supplies water sprayers, bubble machines and scrubbing brushes without specifying how to clean the car’s different parts.

“It goes way beyond washing a car and taps into critical thinking,” said Mary Weiland, senior exhibit developer.

On Wednesday, the car wash made 5-year-old Siena Maynard pause and look to her nanny, Pa Vang, for directions.

“She’s a big rule follower and likes structure,” Vang said. “When we got here, she asked, ‘What do we do?’ and I said, ‘Grab some raincoats and brushes.’ ”

That was all Siena needed to get to work. Before long, she had rolled up her orange coat sleeves and was scrubbing away at the car’s tire. Nearby, 3-year-old Jett Rohrbaugh pitched into the washing with fistfuls of suds.

“He just jumped in and started playing,” said Nicole Rohrbaugh, his mom. “Kids love water and to pretend they’re doing what adults do. He was really drawn to the car.”

The hodgepodge car was built with parts from at least 13 different vehicles — many saved from junkyards. There’s the bright yellow front, taken from a Volkswagen beetle. The back end was once part of a Metro Transit bus. And one of the doors came courtesy of St. Paul police, who donated it from an old cruiser.

The car reminds Kate Donaldson, one of the museum’s founders, of the museum’s early years of resourceful scavenging — from nabbing donated TV monitors from a local television station to making pacts with garbage collectors combing alleys.

“We used everything we could get our hands on,” Donaldson said.

All three founders were young mothers at the time, she said, and that meant planning at the park and around kitchen tables before the museum opened in downtown Minneapolis in 1981. The museum, which moved to Bandana Square in 1985 and downtown St. Paul in 1995, now draws more than 460,000 visitors a year.

Much of the building will be gutted during construction, with new activities and designs replacing all of the existing exhibits before it reopens next spring.

“It’s like seeing a child all grown up,” Donaldson said.