Summer school numbers are up dramatically in Fresno Unified, which now requires students earning D's and F's to attend.
It's part of a new emphasis to keep struggling students -- from elementary through high school -- on track for graduation and meet the district's goal of proficiency, which means earning C's or better.
Some students are taking summer classes to get a leg up on their studies for the coming school year.
But most who are enrolled are required to be in school this summer, officials said.
Summer classes are offered in two sessions, the first ending Thursday and the second ending July 22. Nearly 8,000 students are enrolled for the first session, up 46% from last year.
Some students have to enroll in both sessions, others in only one. It depends on a number of factors, including whether students failed an entire year of a course, or just a semester, during the regular school year.
Fresno Unified is using federal economic stimulus money to hire extra teachers for the summer.
Sixteen-year-old Sara Torres isn't thrilled to be spending her summer break in a classroom at Fresno High School four days a week.
"It's terrible. It's hot," she said. "And you only get a 20-minute lunch break."
And absenteeism is not an option, Sara said: "You can't miss more than two days or you are kicked out."
She flunked the first semester of a required English class last year and must repeat it this summer if she wants to stay on track to graduate next year.
"It sucks, because my other friends get to sleep in and I have to get up early," Sara said.
Unlike Sara, Rebekah Wells is attending summer school voluntarily because she wants to get ahead.
Rebekah, 17, a student at Roosevelt High -- where her dad, Bryan Wells, is principal -- is taking trigonometry this summer so she can take Advanced Placement calculus in the coming school year as a senior.
The district added classes to help AP students get ahead, part of a greater effort to encourage more students to enroll in the academically challenging courses.
For example, incoming high school ninth-graders can take a pre-AP or prep course this summer to prepare them for AP human geography, said Chris Evans, associate superintendent of secondary education for Fresno Unified.
Lauren Ray, 14, will start Edison High School in August and signed up for a high school sociology class so she could fit AP human geography into her upcoming class schedule.
"It's only three weeks," she said. And otherwise, "I would just be sleeping in and hanging out with my friends."
Fresno Unified is offering summer classes at most high schools. Because of renovation projects, no classes are being held at Bullard and only a limited number at Hoover; classes for students from those campuses are being held at Tenaya Middle School.
About half the district's middle schools and about one-third of elementary schools are open for summer school.
So far, most students who earned D's and F's are attending, even though their parents have the ability to excuse them by signing a waiver.
However, a small number of students have failed to show up for class, Evans said.
Some may not have gotten the message that D's now require a summer make-up class.
In these cases, school officials plan to have conversations with their parents.
"Culture change takes time," Evans said.