Of the 2,958 children and teens currently enrolled in summer school, 98 are high school students completing courses such as algebra 1, geometry, biology and world history.
The "second semester" will end July 30. First semester ran from June 21 to July 9.
The two-semester program — squeezed into six weeks of intensive, five-hour days — is a new offering, created in response to pleas from teachers, students and parents, according to Assistant Superintendent Virginia Davis.
Previously, Palo Alto summer school offered at most only one-semester's worth of class.
"Students were having to go to other districts or to private high schools in the area to make up the credits they needed or wanted, so we added the extra weeks," Davis said in an interview Wednesday.
"Our kids have changing and emerging needs, and we're trying to change to address those needs."
About one out of every four Palo Alto students is enrolled in the district's summer school program.
Students sign up for both "enrichment" and "remedial" reasons, according to Davis and Summer School Coordinator Barbara Lancon.
In some cases, high school students need to make up one or even two semesters of a class they failed during the regular school year. In other cases, they seek to complete a course over the summer to make room in their schedule for more academics.
"For some of them it's just a way to take a more intensive school year," Davis said.
"We also have kids who get a B+ and want to take the class again. It's their first experience with getting anything less than an A.
"We're addressing each individual family and spending a lot of time meeting with parents.
Davis said she wished students taking the intense summer school classes would opt to schedule more creative courses during the school year, rather than more Advanced Placement (AP) classes.
"We need to look at creating whole adults, with many interests and abilities."
By far the most popular summer offering at the high-school level is the one-semester "living skills" class, which is required for graduation at both Gunn and Paly.
High school students gathered for class at Terman Middle School this summer because of heavy construction work on the Palo Alto and Gunn high school campuses. Terman remains in session through July 30.
For elementary and middle-school students, the four-week summer session ended July 16.
The middle-school program — almost entirely "enrichment" classes — was held at JLS Middle School and offered courses such as "Hogwarts' Haven," "Let's Draw Manga!" and "Graphic Design."
Elementary schools offered Mandarin and Spanish immersion classes, and both enrichment and remedial courses in math and language arts.
High school summer school enrollment totaled 794 students; middle school 1,111; and elementary school 943.
In addition, 110 rising juniors and seniors took living skills online. Those students were required to complete their work within the three-week session and to meet weekly with a teacher at Terman.
They also had to attend two CPR-first aid sessions at Terman.