Dozens of kids cheered as streams of diet soda shot 20 feet into the air Saturday at the Sonoma County Fairgrounds.
"That was pretty cool," said Lucas Russell, 13, of Rohnert Park.
The Soda and Mentos Reaction Show by the father and son team of Donald and Sutter Laird was a crowd-pleaser at the Bay Area Science Festival's North Bay Discovery Day, which featured about 80 exhibits in a free, daylong event.
But is unleashing mint candies in a capped, two-liter soda bottle, setting off an immediate gaseous geyser, really science?
"It's a physical reaction," said Donald Laird, a Santa Rosa Junior College computer instructor. "All the gas in the bottle bubbles at once. It took us many iterations to get this procedure down."
"If you don't like to get wet, back up," his son, Sutter, advised the crowd circling their exhibit for the 12:30 p.m. show.
Across the lawn, kids were peering at the sun through five telescopes provided by volunteers from the Robert Ferguson Observatory at Sugarloaf Ridge State Park.
"Pretty neat," said Anthony Carreon, 10, of Napa. "It looked red because of the hydrogen."
"He's really into science," declared his sister, Gianna, 8.
The sun appeared as a large orange ball in the telescope Bill Wheeler built, starting with a paper construction tube he bought at Home Depot.
The small dark specks on the surface are sun spots, he said. "The smallest one you can see is bigger than the Earth."
About 10,000 adults and children, mostly elementary and pre-school aged, attended the third annual Discovery Day, sponsored by a host of businesses and organizations and aimed at inspiring students to pursue studies and careers in science, technology, engineering and math.
Gerardo Carreon said it was worth bringing his three kids — Anthony, Gianna and Leah, 3 — to the event.
One of the telescope volunteers spoke Spanish, English and German to the kids, impressing their dad.
"I want to teach my daughter that it's important to communicate," he said.
Petaluma High School students and teachers brought a 70-foot-long forced air-filled model of a blue whale into the Hall of Flowers building.
At a table by the whale, students helped kids make GAK, a 50-50 mix of Elmer's Glue and water mixed in a sandwich bag with a 3 percent Borax solution to make a gummy white substance that resembles silly putty.
"You put your hands in it; it's fun to work with," science teacher Kris Camacho said.
Technically, it's a polymer, made out of long strands of molecules like spaghetti.
Preschooler Kennedy Cobb, 4, of Cazadero followed the directions at a Program in Biotechnology Education exhibit for coaxing DNA out of fresh strawberries by squishing them in a baggy, adding a buffer of water, salt and dishwashing detergent, filtering it through cheesecloth into a tube and layering on some alcohol.
Kennedy said she didn't know what DNA is but wants to be a scientist. What kind of scientist?
One who studies "rocks and sticks and bugs," Kennedy indicated, with help from her mother, Cindy Cobb.
Carson Gibney, 7, of Santa Rosa fired a duct tape-wrapped roll of toilet paper from a supersized slingshot at an Agilent Technologies exhibit, hitting a stack of cardboard boxes.