An additional 10 new classrooms already are under construction or in the pipeline at Ohlone, Fairmeadow and Duveneck schools.
With an unexpected bump in elementary-age enrollment in the past two years that many believe could continue, officials are scrambling to get classrooms ready.
The need for new elementary space — particularly in the southern part of town — means that all available real estate will be scrutinized, including the city-owned former Ventura Elementary School site, the Greendell Elementary School campus now used for pre-school programs and the Hoover and Ohlone campuses, which currently house district-wide "choice programs."
Superintendent Kevin Skelly said the district must prepare itself to handle as many as 568 additional K-5 students in the next five years — the size of a large elementary school.
In a four-hour study session on enrollment and facilities planning Tuesday, school-board members struggled to discern a trend in recent data, saying they hope to match location of the new classrooms to neighborhoods where the growth is occurring.
In the decade before 2009, enrollment growth was fairly even around the city, but the past two years has seen a strong bump in the southern part of town, leading to some children being "overflowed" from their neighborhood schools and sent to others.
"Could it be as simple as driving down Stanford Avenue and seeing all the new houses, or driving down West Bayshore and seeing all the new developments by the JCC (Jewish Community Center)?" board member Camille Townsend asked.
Board member Barb Mitchell argued that new housing developments represent only part of the growth potential. Substantial enrollment increases could come from the north once the real-estate market picks up and older homeowners begin selling to young families, she said.
Anecdotal evidence from new registrations for 2011-12 so far suggests "a lot of new home purchases, and also a lot of older people giving homes to their children," the school district's Central Attendance Director Margie Mitchell said.
At least for the immediate future, Skelly said — and board members seemed to agree — the greatest growth pressure is in the southern part of town.
Of the $98 million allocated for elementary construction in the $378 million facilities bond passed by voters in 2008, $65 million remains available to build new space or upgrade existing classrooms, officials said.
"We don't want to add portables to our campuses, and we don't want to make mistakes here," Skelly said.
"These are millions of dollars. Almost any capacity we build now will be used, but it's also true that we don't want to overbuild and then have lots of empty space."
With current enrollment, some campuses already are using 100 percent of their capacity while others are lower, with a district-wide average of 94.6 percent utilization, officials said. Skelly said he hopes to keep about 5 percent excess capacity for growth once the new classrooms are built.
Many said growth pressures in Palo Alto are likely to continue and even increase as other school districts boost class size and slash their budgets in response to state cuts.
"Palo Alto is becoming a more attractive place for young families to bring their children," Skelly said.
"The premium for good education is up, and surrounding high-quality districts have seen it as well. We need to assume high enrollment projections when we look at facilities."
Skelly said he will return to the board in May or June with more specific recommendations on where to add space, including the possible reclaiming of the Garland site at 870 N. California Ave., now under a lease that requires three years' notice.