D grades no longer are good enough for Fresno Unified School District students. This summer, for the first time, students earning D's -- as well as F's -- will be required to attend summer school.

District officials said it's part of a new emphasis to help all struggling students succeed. Even though a student can pass a class with a D, it doesn't demonstrate proficiency -- the district's goal.

In the past, summer school was optional and primarily focused on students who were flunking class. Under the new rule, the district plans to double the number of students attending summer school at a time when most cash-strapped school districts are cutting summer programs.

The district plans to use some of the millions of dollars received in federal economic stimulus funds to enroll more than 10,000 students.

A state education expert said it's rare to see a school district expand summer school today in light of state budget cuts. But she said it makes sense if the goal is to help struggling students succeed.

"I know that districts were given flexibility with some of their funding, so they are choosing where to focus. This is an interesting choice," said Mary Perry, deputy director of EdSource, a Mountain View-based think tank that focuses on California schools,

"The fact that they are allocating scarce resources to this effort says to me that the district is taking very seriously the need to improve student achievement," Perry said.

In the past, the district has used federal stimulus money to keep teachers on the payroll as well as pay for early retirement incentives.

Expanding summer school will require Fresno Unified to hire more teachers for the summer, which could help Valley educators who recently received notice their jobs could be eliminated due to local district job cuts. At the high school level alone, the number of teachers needed for summer school would jump from 211 to 400.

Unlike past summer school sessions, this year the district will automatically enroll students with D's or F's, said Chris Evans, associate superintendent of secondary education for Fresno Unified School District. Students will be excused only if a parent signs a waiver.

Evans said he doubts parents will opt to keep their children out of summer school. "Most parents, when they really understand the gravity of the situation, will be supportive," he said.

The district will mail letters to parents in the next two weeks. Students who earn a D or F in the first semester only, but improve to a C or better by the end of the year, will have to complete only half the summer session.

Some 57% of high school students earned a D or F by the end of this school year's first semester -- down from 59% last year, Evans said. "It's higher than we want to see it," he said, but the rate is similar to other districts Fresno Unified's size.

All seven comprehensive high schools will be open for summer school, as well as nearly half the district's middle and elementary schools.

District officials said the goal is to help K-12 students who are in danger of falling behind to succeed and stay on the path to graduate and go on to college or a career.

"It's not just about summer school, it's about extending the school year to support our students," Evans said.

The district also will expand Advanced Placement offerings over the summer.

Fresno Unified's growing summer school program counters the statewide trend of cutting summer classes.

Officials with the California Department of Education said summer school programs have been axed because of budget cuts, limiting students' opportunities to learn.