Josh Bonanno peered into the 400-power microscope at the Buck Institute for Research on Aging, a world-class science facility in Novato.
His fifth-grade classmates from Sequoia School in Rincon Valley let out oohs and aahs as they saw on an adjacent monitor the throng of bacteria grown from a swab Josh took last week at school.
"There was like seven big brown blobs," Josh said. "The rest was all yellowish."
Julie Mangada, the K-12 education coordinator at the Buck Institute, said she could tell just from holding up the clear plastic petri dish that Josh had corralled a bacterial bonanza.
"There's so much stuff in this one," said Mangada, a Santa Rosa resident who has a doctoral degree in molecular medicine.
"Jackpot, Josh," Sequoia teacher Rhiannon King said approvingly.
Where did he find so many germs? "Inside the toilet," Josh said.
Sequoia's entire fifth-grade class, about 60 students, on Tuesday made the first school field trip to Buck's brand new $500,000 Learning Center, a training and demonstration space for visitors of all ages, or "K to gray," as Mangada put it.
Last year, more than 1,700 students visited the institute, housed in a white limestone-clad building overlooking Highway 101 at the north end of Novato. It's where about 200 scientists work on solutions to age-related conditions, such as Alzheimer's and Parkinson's diseases, cancer, diabetes and stroke.
The number of student visitors will grow now that the Learning Center is open, with a DNA double-helix design embedded in the floor and work tables soon to be lining the walls.
Tuesday's lesson was about bacteria, the mostly benign organisms -- ten-thousandth of a centimeter long -- that live almost everywhere on Earth and thrive on the skin and in the gut of humans.
The students, under Sequoia science teacher Wendy Schwartz's direction, came well prepared.