School days: Students start high school with visit to UC Berkeley.

Many adults wouldn’t mind having fewer moody, hormonal teenagers around. But for administrators in the San Francisco Unified School District, the increasing lack of high school students is a real problem.

Public school starts Monday, and while elementary school and middle school enrollment continues to grow, high school enrollment is tapering off like attendance in the spring semester of senior year.

Preliminary enrollment figures show 56,964 students for the new school year, up about 650 students from last year. Students generally apply for new schools in kindergarten, sixth grade and ninth grade. There are 5,069 tykes enrolled to start kindergarten Monday, and 3,584 sixth-graders set to enroll, continuing an upward trend for both.

High school, though, is a different story. The district last year received 4,603 applications for ninth grade, but this year’s figure sank to 4,188. And just 4,073 are actually enrolled to start Monday. Gentle Blythe, a spokeswoman for the school district, said demographers have long predicted shrinking high school enrollment, a trend that is expected to continue for several years.

This reflects the 2010 census figures for San Francisco, which showed 3,000 more children younger than 5 years old than 10 years ago, but 8,000 fewer school-age kids. City officials mostly blame San Francisco’s bleeding of families on a lack of affordable family housing and the high cost of living in general, but many families say the city’s public schools are also a contributing factor in their decision to leave when their kids get older.

For the school district, that means fewer dollars from the state, which funds districts

based on per-pupil enrollment, and a potential glut of underused buildings to maintain or sell.

Blythe said no decisions have been made about how to respond to declining high school enrollment.

“The district is examining enrollment trends and exploring various scenarios for addressing declining enrollment at high school,” she said.

Jill Wynns, a school board member, said that for the new school year the popular high schools won’t see much change, but that it’ll mean fewer students at the less popular schools, most of which are on the east side of the city. She said it’s certainly possible that the district will have to close one of those schools in the next few years. But she added that the hope is that all those elementary students will stick around through high school graduation and that administrators don’t want to close a high school if it’ll eventually be needed.

“We’d like to keep all the schools open,” she said. “The cycle goes around and around.”

With summer recess in full swing in City Hall, we thought it was time to ask Mayor Ed Lee to rate his own performance midway through his first year without the word “interim” in front of his title.

“I think everybody been working pretty hard to keep focus,” he said, ticking off his proudest accomplishments, such as getting a payroll tax reform measure and parks bond on the November ballot, crafting a two-year budget and putting together plans for a housing trust fund.

Note the promise of a new Warriors arena at Piers 30-32 did not make his list, though he said when it was announced in the spring it would be his legacy. Maybe he just forgot.

Lee said there haven’t been any real disappointments or failures so far, but that it is more challenging being just plain mayor rather than the interim mayor.

“I won’t go into details, but there are a lot more politics,” he said. “I did shy away from that and I still do.”

Well, he doesn’t always shy away from it, but maybe he should. Take the ill-fated proposal of bringing New York City’s stop-and-frisk policy to San Francisco, which nobody but Lee seemed to think was a good idea and he eventually dropped.

No midyear report would be complete without a letter grade, and we asked Lee to assign one to himself.

“Oh geez, I’m not used to grading myself,” he said. “I hope that the grade will come in the public in November supporting in overwhelming majorities what we’re trying to do. Then I’ll subject myself to that grading.”

So it’s an incomplete then?

“Incomplete!” he said good naturedly. “Right!”