Gunn High School sophomore Sarah Grossman-Kahn had the full attention of five third-graders at Barron Park School, their eyes intent on a makeshift contraption with dangling red and green magnets.
Sprawled on a carpet nearby, another group of third-graders shrieked with glee as Gunn students Andrew Gerber-Duffy and Jaxon Welsh pushed ball bearings along a rail to demonstrate the law of conservation of energy.
Just outside the door, students took turns twirling a blue bucket full of water in exuberant shows of centripetal force under the direction of Gunn sophomore Foster Cheng.
Teens in Gunn's student-run Science Alliance recently visited both Barron Park and Nixon schools bearing their hands-on projects, intended to convey the joys of chemistry and physics.
"We have a passion for science, and we want to share it with elementary schools and hopefully spark some interest in science, engineering and mathematics for another generation of students," said Science Alliance President Derek Nielsen, a senior at Gunn.
"We're not there to preach to the kids or give them a lecture. We want to excite them and hopefully give them one or two science concepts along the way."
Nielsen, who joined Science Alliance his sophomore year, plans to study mechanical engineering in college.
The five-year-old student group has amassed a repertoire of hands-on demos, and members try to come up with a few new ones each year.
"We look on the Internet or do our own research to come up with safe, interesting, easy enough demos," he said.
Established crowd-pleasers include a plasma ball to demonstrate principles of conductivity and fluorescence; a Van de Graaf generator, which allows students to see shocks of static electricity and "instant snow" -- a hyper absorbent polymer.
Nielsen, who attended Barron Park himself, recalls the day the Gunn Robotics Team visited the school when he was in fifth grade.
"When you bring in someone who's not a teacher, it's almost on a peer-to-peer level with students and it's a different dynamic," he said.
"We see a lot of interaction and discussion, and the teachers have commented on that."
In education-minded Palo Alto, it's not unusual for the Gunn volunteers to encounter kids who already know the answers, he said.
"Many of the kids here are very precocious. They're children of Stanford professors or they've been to the Tech Museum every weekend. Sometimes they know exactly what we're going to tell them," he said.
"We'd like to expand to some schools that don't have that demographic."
Science Alliance has had trouble in the past gaining access to some schools "because they're kind of wary of high school students bringing in a science program.
"But we've come back to Nixon several years in a row now and they're enamored of our program," Nielsen said.
The Gunn volunteers' recent visit to Barron Park was a first for that campus.
"This is a building block for students to get a better understanding of the concepts of physics," said Barron Park teacher Nick Foote, noting that his third graders had recently covered a unit on matter and energy.
"It's great to convey these rather difficult science concepts in a way the kids can understand through moving, seeing and physically doing."