At Gunn, the 26 portable classrooms that comprised the "Titan Village" section of campus have been moved to the parking lot to make way for construction of a new, two-story building for the math and English departments.
At Paly, the campus is abuzz with "belly dump" trailers, bulldozers, backhoes and motor graders.
The Churchill Avenue field containing baseball and softball diamonds has been dug up — resembling a moonscape studded with mounds of dirt and gravel — and will not re-open until February.
And the entire central campus is fenced off as workers assemble 16 portable classrooms in the Paly quad.
The work — funded by a $378 million facilities bond that was approved by 77.5 percent of school district voters in June 2008 — eventually will touch all 17 campuses of the Palo Alto Unified School District.
The bond program is intended to modernize outdated classrooms and expand school capacity to accommodate anticipated enrollment growth.
Now at 11,680 students, district-wide enrollment has crept up steadily from a low of 7,452 in 1989-1990.
The previous high point was at the crest of the Baby Boom years in 1967-68, when enrollment was 15,575 and Palo Alto had three comprehensive high schools.
Enrollment had dropped to about 11,000 by 1979, when Cubberley High School was closed.
"We don't know what will happen with enrollment — we certainly wish we did," School Superintendent Kevin Skelly said in a meeting last month.
"But if you look at the last 20 years it seems that our enrollment is impervious to some factors. Whether the economy is good or bad, enrollment continues to increase."
Skelly said the bond measure projects "take us to capacity" at the district's three middle schools and two high schools.
"If it were to go well above that, we'd certainly have to consider another middle school or another high school," he said, speaking at a June 16 joint meeting of the Palo Alto City Council and the boards of the Palo Alto Unified School District and the Foothill-De Anza Community College District regarding the future of Cubberley.
The summer changes at the high schools are aimed at clearing space for construction of brand-new facilities.
At Paly, portables were cleared from a spot near Embarcadero Road as well as from a quad near the school's corporation yard to create construction space for a Media Arts building and a two-story classroom building that will house the math and social studies departments.
Workers are under tight deadlines to have the quad portables hooked up and ready to go by Aug. 13 so that teachers can move in on Aug. 16.
The first day of school for students is Tuesday, Aug. 24.
Groundbreaking on the new structures themselves could be as late as next spring or summer, depending on the speed of state approvals.
Plans for the new buildings on both high school campuses will be submitted within the next four weeks to the Division of State Architect, charged with oversight of all school construction, according to Thomas Hodges, a senior vice-president of O'Connor Construction Management Inc. and program director for the school-district projects.
The Board of Education, at the recommendation of site committees at both high schools, decided to move the portables this summer rather than wait a year so that construction could begin quickly once the projects clear the Division of State Architect, expected to take up to nine months.