The Children’s Discovery Museum was almost complete in 1990 when one detail became a sticking point: the bright pink color planned for the Ricardo Legorreta-designed building in downtown San Jose just wouldn’t do.

“That Pepto pink was too precious,” said Sally Osberg, the museum’s founding executive director who is now president at the Skoll Foundation. “The purple is playful, and it’s lyrical,” she said about one of the most pleasing options. ” When the jacaranda trees are in bloom in front of the museum, there is just something magical about the color.”

Osberg, as usual, made the right call. Since then, the famed museum — with its huge yellow mascot, Discovery Duck, usually floating on the roof — has become a lavender landmark for families around the Bay Area, drawing more than 7.7 million visitors in the 25 years since it opened.

Children and parents play with the gravity well at the Children’s Discovery Museum in San Jose, Calif., on Wednesday, June 17, 2015.

But for Osberg, it’s not how the museum looks, but how its culture made it so successful. “The beauty of the Children’s Discovery Museum is that it just gets better and better and better,” she said. “One of my great joys is seeing how new and vital it remains.”

Friday night, the Children’s Discovery Museum celebrated its silver anniversary at its Legacy for Children Award dinner, which honored both Osberg and Apple co-founder Steve Wozniak, the museum’s founding donor, who contributed $1.8 million toward its construction. More than 800 people attended the dinner at the San Jose McEnery Convention Center, which included a surprise performance by Bay Area musician Michael Franti.

The event also marked the official launch of a 27,500 square-foot, $2 million outdoor expansion that will take the museum’s mission of hands-on education beyond the colorful walls and let kids dig into the environment around them. The exhibits will include four rain cisterns, a dry creek bed, solar panels and an expanded “taste and touch” garden. The centerpiece of the space will be Treetop Adventure, a tree-climbing and tunnel exhibit, but the most eye-catching may be the “Tree of 40 Fruit,” a hybridized fruit tree grafted with multiple varieties of stone fruit created by artist Sam Van Aken.

“It’s just fantastic, but it’s taken a long time to get here,” said Marilee Jennings, the museum’s current executive director. Like Osberg, her history with the museum goes back to the original campaign to realize a fun and lively children’s museum dreamed up by two Santa Clara County moms, Carolyn Nelson and Reba Wehrly.

Osberg arrived in 1983 charged with overseeing the fundraising campaign, which included a pitch to Silicon Valley tech companies like Apple and Atari. After hearing the plan to let children explore nature, science and other cultures, Wozniak said he was frustrated because it sounded like something that he would have really wanted to have been part of. But the plan for the San Jose museum sounded so complete, he thought he’d missed the boat.

“They said well we’re actually only in the planning stage. The next stage is one called money. Oh, I felt so great. I had an in,” Wozniak recalled. “The important thing is recognizing good people that care about what they were doing and had great ideas and wanted to change the world for children in social matters.”

Tom McEnery, who was San Jose’s mayor during the project’s planning and completion, says Wozniak’s involvement was paramount. “He’s dollar-for-dollar in the same category as Hewlett and Packard and all the great philanthropists,” McEnery said.

The museum’s original goal was to acquaint kids with the world around them. In 1990, that meant a city street scene, complete with a fire truck, ambulance, Wells Fargo stage coach, stop lights and street markings. Those features are still there today, though the ambulance has been upgraded, but other 20th century fixtures like a bank and a post office have been replaced. Kids still don protective aprons and watch the course of plastic balls in the WaterWays exhibit or turn soapy water into giant, iridescent shapes in the Bubbles exhibit. And youngsters still crowd around to make their own cornhusk doll, a museum keepsake that remains Jennings’ favorite exhibit.

But today’s visitors have opportunities unimagined by yesterday’s children. There are mammoth bones to be explored, traveling exhibitions featuring Nickelodeon stars Dora and Diego and a musical staircase that leads up to the Art Loft and the Wonder Cabinet, a mind-stimulating haven for kids 5 and under.

Outreach programs to the Latino and Vietnamese communities have led to regular cultural events and even “Voyage to Vietnam,” an exhibit created by the Children’s Discovery Museum to celebrate Tet that will travel to other U.S. cities when it ends its run in San Jose this fall.

This summer, the museum’s cafe is being transformed into FoodShed, featuring healthier options that align with the museum’s nearby Rainbow Market exhibit. Locally sourced produce and other ingredients from around the Bay Area are in; Sugary sodas and french fries are out. “We wanted the cafe to feel like the rest of the museum,” said Jennings.

The expanded outdoor space also feels like a twist on the Children’s Discovery Museum’s mission, which focused on finding your way around the urban world. But here in the center of technological innovation, the ongoing drought, the farm-to-table movement and climate change concerns have encouraged a greater exploration of the natural world just on the other side of our computer screens — activities that would have been old hat to the kids growing up in the then-agricultural Santa Clara Valley of the mid-20th century.

The new space is being called “Bill’s Backyard” in honor of Bill Sullivan, the CEO of Agilent Technologies who retired in March. Agilent was looking for a lasting way to honor Sullivan, who sits on the Children’s Discovery Museum board, and provided the seed funding for the project.

“When Bill found out about it,” Jennings recalled, “he told me, ‘It sure beats a gold watch.”

And it’s a great way to celebrate an anniversary.

Contact Sal Pizarro at spizarro@mercurynews.com or 408-920-5473. Follow him at Facebook.com/mercurynews.aroundtown and Twitter.com/spizarro.

CHILDREN’S DISCOVERY MUSEUM AT 25

A look at the first quarter-century of the Children’s Discovery Museum in San Jose:

June 2-3, 1990: After seven years of planning and two years of construction, the museum opens in downtown San Jose. Attendance is expected to be 155,000 people annually; 340,000 people visit in the first full year of operation.
1996: The City of San Jose provides the museum’s “west wing” space for a gallery for traveling exhibits.
1996: Latino outreach efforts are launched, including a “Dia de los Tres Reyes” celebration that draws 5,000 visitors every January.
1999: The first Legacy for Children Award is presented to Fred Rogers. Later recipients include Rob Reiner, “Family Circus” creator Bil Keane; Theodore “Dr. Seuss” Geisel; Sally Ride; and Alice Waters.
2001: First lady Laura Bush bestows CDM with the National Medal for Museum Service.
2002: Connie Martinez becomes executive director, replacing founding executive director Sally Osberg, who left to become president of the Skoll Foundation.
2005: The Wonder Cabinet, a gallery space and learning laboratory geared toward children under 5, opens.
2005: Outreach to the Vietnamese community results in the development of “Children of the Dragon,” a new annual celebration.
2007: Marilee Jennings becomes executive director.
2010: In time for the museum’s 20th anniversary, Mammoth Discovery!, an interactive exhibit with a skeletal replica and a 2-ton mammoth sculpture outside, opens.
2013: Healthy eating education becomes a priority with the creation of the Rainbow Market adjacent to the outdoor kids garden.
2014: With funding from the Freeman Foundation, CDM creates “Voyage to Vietnam,” a 1,500 square-foot interactive exhibit to celebrate Tet that will travel to eight U.S. cities.
2015: Construction begins on the Builder Building, a 3,200 square-foot on-site facility for exhibit fabrication and maintenance.

Source: Children’s Discovery Museum

Five things you didn’t know about the Children’s Discovery Museum in San Jose:

  • The address, 180 Woz Way, pays tribute not only to primary donor Steve Wozniak but to the $1.8 million he gave the museum.
  • As of its community birthday party June 6, more than 7.7 million people had visited to the museum.
  • Opera San Jose had a rehearsal space at the Children’s Discovery Museum for the museum’s first few years.
  • Founders Carolyn Nelson and Reba Wehrly were inspired by the hands-on focus of the Boston Children’s Museum, where Sally Osberg, CDM’s founding executive director, had worked as an intern.
  • The building was designed by Mexico City-based architect Ricardo Legorreta, who later designed the Tech Museum of Innovation.

    IF YOU GO

    Where: Children’s Discovery Museum, 180 Woz Way, San Jose
    Hours: Open Monday through Saturday, 10 a.m. to 5 p.m.; Sunday, noon to 5 p.m. (Hours change seasonally)
    Admission: $12 for adults and children 1 and older; $11, adults over 60
    Website: www.cdm.org