Ask a teacher at San Marcos High “what’s the big deal” about the school’s beloved 90-minute periods — a unique setup known as the “block schedule” — and you’ll get two ears full.

With the Santa Barbara school districts’ three high schools competing with one another for students, the block schedule is a defining feature for San Marcos, which uses the longer periods as a selling point for students who prefer to concentrate on fewer classes at once.

Now, teachers fear the block schedule could become collateral damage in a budget crisis that will culminate Tuesday, when school trustees are expected to cut $4 million from the $93 million discretionary budget for the 2008-09 school year.

Administrators insist it isn’t the block schedule they want to do away with but rather a disparity that puts the price tag of staffing San Marcos about $560,000 higher than at Dos Pueblos and Santa Barbara high schools.

But first: What is the block schedule?

At San Marcos, it means the day is broken up into four 90-minute periods, instead of six 55-minute periods. Also, the school year is broken into four quarters vs. two semesters. A class that would take a full year in a traditional setting takes a half-year at San Marcos.

Not everyone agrees it’s the best way for students to learn.

Some critics say the block-schedule periods are too long to hold most students’ attention, or that it impedes their ability to perform well on standardized tests, because the lapsed time from the first-quarter classes demands more of their memory.

But at San Marcos, which has adhered to the block schedule since 1994, many teachers say they swear by it.

English teacher Jack Hobbs says the block schedule fosters more in-depth classroom discussion.

“When I taught regular 55-minute periods, it seemed like we were always getting to the point where discussion was beginning to take off, and the bell would ring,” he said.

Advanced Placement history instructor Eric Burrows said it’s a better way to prepare students for college, because college students tend to take three intensive courses at once.

Performing arts teacher David Holmes said research has debunked the retention criticism. He added that despite this, at San Marcos many teachers offer study sessions throughout the year to guard against memory loss.

There’s another common criticism that raises Holmes’ dander: Teachers prefer the block schedule because it is convenient.

“People say it’s easy on the teachers; it’s not easy on the teachers — that’s a load of crap,” he said.

Rather, he said, like students who prefer the block schedule, teachers who prefer it enjoy having fewer classes to prepare for at any given time. But it all evens out: While faculty at the other high schools teach five classes a year on average, teachers at San Marcos tend to teach six — three each semester.

“I’m willing to teach another class above and beyond the contract for the same amount of money because, one, the class sizes are smaller, and two, I’m able to teach a very pure section of drama that I was never able to teach before,” Holmes said.

Students, too, seem to prefer the block schedule. Of the handful who were interviewed by Noozhawk, all were supporters.

Sophomore Harrison Strober said it better allows him to take two electives: drum line and tennis.

“One of the main reasons I came here was for the block schedule,” he said, although he admitted it sometimes made testing more difficult. “It is kind of a bummer when you know the answers but just forgot them.”

“I like how I’m able to focus deeply on three main subjects, as opposed to six or seven,” she said. “And not have to worry about so much of the scattering that goes on at so many of the other schools.”

Superintendent Brian Sarvis said the district has no intention of obliterating the block schedule.

“I periodically hear that someone is trying to axe the block schedule or something, and it is absolutely not true,” he said. “The simple fact is it costs the district more to staff San Marcos than to staff other schools with comparable enrollment.”

However, when asked if he thought San Marcos would lose its block schedule if staffing parity were achieved, he equivocated.

“I don’t think that’s true,” Sarvis said. “I want them to figure out a way to keep the block schedule and reduce the additional expense to the district.”

Meanwhile, the confusion surrounding the teachers’ suspicion vs. the administrators’ stated intentions centers on the fact that the argument is all about math.

Because the block schedule frees faculty to teach that extra sixth class, San Marcos is able to keep class sizes lower than the other schools. As a result, San Marcos’ average class size has always been smaller than that of the traditional schools, but, paradoxically, the number of students taught by its instructors throughout the year tends to be higher.

In any case, San Marcos’ smaller class sizes played a key role leading to the school’s predicament. Two years ago, when the district and the teachers union negotiated a contract, they capped maximum class sizes. Taking note of San Marcos’ ability to keep class sizes small, district officials granted the school a lower cap — 31 students per teacher vs. the 35 received by the other two schools. Ultimately, however, that idea amounted to giving San Marcos an unexpected reprieve from the staff reductions that befell the other two schools. In fact, San Marcos actually gained teachers.

Now, the district has caught the discrepancy. To achieve parity, the class-size cap at San Marcos needs to be commensurate with that of the other two schools, Assistant Superintendent Paul Turnbull said.

Teachers at San Marcos concede that parity is fair, but they insist that leveling the playing field in one year would decimate the block schedule.

“If you have an advantage on your taxes because of a mistake, are you going to have to pay for that?” Holmes aked. “Yes. But if we were to pay for that in one year … it would be a bloodbath.”

Teachers at the school are hoping the board will opt to try to correct the discrepancy in two years, rather than one.

But doesn’t that merely forestall the inevitable? Maybe, Holmes said, but not necessarily, because this summer, the district and the teachers union will begin negotiating a new contract.

Holmes said he is hoping the district, at that point, will do away with the concept of a class-size cap.