The news came following a lottery held last week for prospective kindergartners at the two schools — necessitated after more children signed up at the two campuses than there are currently available spots.
It's possible that most or all of the children will clear the wait lists by the time school begins Aug. 23. Many families change plans or move their children to district "choice" programs such as Hoover and Ohlone schools, resulting in space freeing up for neighborhood children waiting for spots at oversubscribed campuses, school officials have said.
The numbers of "overflowed" children were 31 for Addison and 10 for Palo Verde.
Wait-listed Addison parents said they were told that up to 20 "overflowed" children in previous years ultimately got a spot at the school.
Kindergartners who do not clear the wait list for their neighborhood schools are typically assigned to another campus nearby. In the case of Addison, that likely would be Walter Hays.
Wait-listed parents described their situation as disappointing and inconvenient as they scrambled to make tentative plans for their kids to go elsewhere.
Overflows have occurred regularly in recent years as the school district has seen steady and sometimes unexpected bursts in enrollment.
Demographers who consult for the school district have said last fall's kindergarten and first-grade enrollment numbers were "surprisingly high," far exceeding previously reliable predictors such as data on local birth records and housing turnover.
Unless those growth rates slow down in the next few years, district officials have said they will prepare for growth at the high end of demographic projections.
Growth has been particularly strong in the elementary grades and in the southern part of town.
School district Superintendent Kevin Skelly said last month that by May or June he would recommend placement of up to 30 new elementary classrooms to be built in the next five years.
Those would be in addition to the 10 new classrooms already under construction or in the pipeline at Ohlone and Duveneck elementary schools. The classrooms will be built with funds from a $378 million facilities bond — to modernize and boost capacity of campuses district-wide — backed by 77.5 percent of voters in 2008.
One factor certain to slow enrollment growth, at least temporarily, is a new "kindergarten readiness" law, to be phased in starting in fall of 2012. The new law — requiring that children turn 5 by Sept. 1 rather than Dec. 2 of the year they start kindergarten — will reduce the size of incoming kindergarten classes for three years. Those reductions will continue to be felt for the next 13 years as the smaller cohorts work their way through the system.
Palo Alto's district-wide enrollment, at 12,024 last September, has been on a steady upward trajectory since a post-Baby Boom low in 1989.
At its historic high in 1968 — when Palo Alto had three comprehensive high schools and more than 20 elementary schools — enrollment was 15,575. Currently the district operates two high schools, three middle schools and 12 elementary campuses.