Helios New School, launched in a home with a handful of students five years ago, now leases a colorful corner of Palo Alto's Oshman Family Jewish Community Center with a K-5 enrollment of 35 children.
Synapse School in Menlo Park offers a similar program for children K-8.
Both schools say they use a "qualitative assessment" of giftedness in children that goes beyond the traditional IQ definition.
Another group, the one-year-old Gifted Support Center, offers assessments, support and community for gifted children and their parents, many of whom resort to home schooling after finding their children are bored or do not fit well in regular classrooms, according to support center director Ann Smith.
The broader definition of giftedness — encompassing characteristics such as reasoning, energy level, attention span, moral sensitivity and "excitability" — has gained ground with some local parents at the same time that public schools generally have pulled back on special offerings for gifted children.
Strapped for funds, the California Legislature in 2008 loosened restrictions on the state's Gifted and Talented Education program, allowing school districts to keep the funds but redirect them to other educational needs.
As a result, the Palo Alto school district suspended the program it once had of identifying gifted children — beginning in spring of third grade — through standardized test scores and checklists of multiple intelligences and indicators of giftedness.
Once identified, children in Palo Alto's GATE program were supposed to be offered "differentiated instruction" and extended curriculum within their regular classes.
"The district remains committed to serving the individual needs of high achieving and gifted students regardless of GATE identification," according to the district's website.
Superintendent Kevin Skelly noted, "In a place like Palo Alto we have an extraordinary number of gifted kids."
Palo Alto public school families seeking greater academic challenge are directed to a long list of enrichment opportunities, from Stanford University's Education Program for Gifted Youth to a variety of math and robotics competitions and spelling bees.
But private educators who embrace the qualitative definition of giftedness say gifted kids frequently have social, emotional and other needs that go unmet in the mainstream classroom.
"We're not talking about high ability across the board," said Anne Beneventi, a founder and current co-director of Helios New School.
"They often have asynchronous development and sometimes they can have a learning disability. What our kids have in common is they need more depth and complexity and need it connected to something (like a project or theme) instead of it being just based on skills."
Helios organizes children loosely by age but forms ability groupings in subjects like math, where some students are working far above grade level.
The father of one Helios first-grader said his son was fascinated with physics and science and could read 200-page books in preschool but had the social skills of any preschooler.
"It's not like we were trying to make our kid out to be super-smart or anything like that, but he certainly was different and showed a lot of signs that, in hindsight, were pretty clear," said the Palo Alto resident, who asked not to be identified.
"Here you had a 3-year-old who wanted to talk about the Period Table of the Elements, and he'd go to talk to other kids about it and they'd say, 'What's wrong with you?'
"He didn't have the social skills to navigate that. He was aware that his interests were different and that led to him feeling isolated and not fitting in. And that makes it very challenging as you go through your early development."
Beneventi introduced the family to another, who had a child with a similar interest in science.
"On the first play date it was eye-opening for (the other mother) because she'd never seen her son engage like that," the Helios parent said.
"You had 4-and-a-half-year-old kids who were playing just like 4-and-a-half-year-old kids but happened to be making jokes about chemistry. Neither had ever had a peer to engage with on that level."
Though the other child does not attend Helios, the two boys still play together regularly, the father said.
Palo Alto resident Ivonne Mena King, mother of another Helios first-grader, said she and her husband chose the school for kindergarten for their child after touring private and public schools.
"One of the many things that sets Helios apart is that children are encouraged to be scientists in all aspects," King said.
"They are not taught to merely sit still and absorb information. For a variety of subjects, the class last year conducted hands-on group or individual experiments.
"Another aspect of Helios that my son loves is exploration. A few times a week, the children are encouraged to explore a subject of their own choosing," King said.
Ann Smith of the Gifted Support Center got introduced to the field when one of her three children began having temper tantrums after kindergarten in a traditional school.
"We had some educational testing done, and it was recommended that we home-school her or put her in a school for gifted children," Smith said.
"At that time I said, 'What's a gifted child?' I would have thought Einstein. That's how the path began for our family."
The family tried home-schooling for awhile, and the child now attends Odyssey School, an independent middle school for gifted students in San Mateo.
The 45-year-old, pre-K-8 Nueva School in Hillsborough is the most widely recognized school for gifted children on the Peninsula, but Smith said the school has a limited number of spots and some families are looking for an option closer to home.
"Giftedness, the way it makes the most sense to me, is a way of experiencing and perceiving the world that includes heightened sensitivity, intensities, advanced cognitive abilities — a way of perceiving things a bit upside of the way normal people experience it," she said.
"Our society tends not to like the word. It's viewed as elitist. The prevailing notion is 'If these children are so smart, they'll be just fine on their own.'
"That's a shame because all children need help to reach their potential."