Because of the high interest level, the district plans to offer the two semesters again in the summer of 2011.
But officials warned the two-semester classes are not meant for students trying to jump ahead — taking summer school biology or history, for example, in order to skip the regular full-year course — but rather for students who need to make up a semester or improve an unsatisfactory "D" or "F" grade.
While this year's summer headcount was slightly down at the elementary and middle school levels, high-school enrollment jumped by 337. Overall, nearly 3,000 — a quarter of all Palo Alto students — attended summer school, 943 at the elementary level, 1,111 middle-schoolers and 931 high school students.
For struggling students, summer is a time to catch up — or just to stay even. Many receive personal "invitations" to attend summer school, based on teacher recommendations, district officials said.
At the elementary level, 434 students received intensive "intervention" support in small classes focused on literacy or math.
In middle school, the literacy and math intervention programs served 126 students.
But the majority of middle school students in summer school are there for sheer fun, taking classes such as Teenage Gourmet Cooking; Math Circles; Myths and Legends; Reading/Writing Festival; Learning Strategies; Bridges, Towers and Windmills: Graphic Design and Let's Draw Manga.
The most popular high school class was Living Skills — and this year, for the first time, an online version was offered.
However, students were required to show up in person at least once a week, leading to some "misunderstandings with a few parents," according to Assistant Superintendent Virginia Davis.
"It didn't mean you could perhaps go on a trip around the world and do all distance learning," she said.
"Students had to be there for a class a week to check in; there was a lot of collaborative work and also a CPR class they had to take.
"It's more of a hybrid. There is distance learning, but you definitely had to be present to learn."
In the first-time-ever second semester, the high school offered seven classes, including semester two of World History, Biology, Algebra I and Geometry.
The high school summer program is aimed at students who need to make up a class, improve an unsatisfactory grade, or want to make more space in their schedules during the academic year.
To guard against students trying to skip a regular, full-year course, students were required to obtain counselor or teacher approval to enroll in many of those classes.
Summer school "is not to accelerate kids ... so they can load their classes again," Davis said.
"We really want students to take the classes during the regular year, if possible. We don't want them to race through school."
Summer school also ran programs for special-education students — four classes at the elementary level, six in middle school and two in high school levels.
Davis proposes to run next year's summer school from June 20 to July 29, with some offerings as short as 10 days and others running two semesters at three weeks each.
She also proposes a 5 percent hike in tuition, bringing the traditional elementary program to $450, one high-school semester to $535 and two high-school semesters to $875.
Low-income students — identified by their qualification for the federal free- and reduced-price school lunch program — are not asked to pay summer school tuition, she said.
Summer school, which ran at a $170,000 deficit in 2009, ended in the black this year, with an excess of $4,400.