In 1972 Prince George's County operated 236 schools to educate some 162,000 students, the ninth largest school system in the country. New classrooms were being built at the rate of one per day.

There was no TRIM tax limitation measure on the books then and the county had one of the highest property tax rates in the region. Enforcement of a court-ordered desegregation plan was still six months away.

This fall Prince George's will rank 13th in the number of students nationally. School officials expect only 116,000 pupils to enroll next week, down from 121,000 just last year.

Now that the baby boom years are finally over the school system will be shutting classrooms at the rate of almost one per day for the next two years. The closing of 18 elementaries and four junior highs as of last June will leave only 194 schools, an 18 percent decline in the actual number of buildings since 1972.

And since the 1978 election of County Executive Lawrence J. Hogan and voter approval of TRIM, the school board has been under constant pressure to trim its budget. Hogan and the County Council cut the property tax rate by 7 1/2 cents this year, a 27 percent drop since 1978. The action means that despite the savings from closings there will be no new programs in the schools this year.

"The budget is tight," said school spokesman Brian J. Porter. "There is no room for extravagant purchases of new materials. We're in the process of re-binding books, repairing broken equipment and reusing materials that in another time might have been thrown away."

Porter maintained, however, that the schools are "moving forward with less." He pointed to test scores of third-, fifth-, eighth- and tenth-graders last spring that were equal to, and in a few cases exceeded, national averages in language, reading, spelling and mathematics.

And there will be a few modest improvements in the instruction program this year including:

* A formal curriculum for the talented and gifted program (TAG) at the senior high level that did not exist before.

Expanding from 14 schools to 55 schools a successful pilot program that places greater emphasis on teaching of reading and writing in kindergarten and the first grade.

* Opening 12 schools that will include grades seven and eight only, as the planned four year phase-out of the traditional three-year junior high schools begins. The middle schools will focus more attention on the personal development and maturation problems unique to educating 11- to 13-year-olds.

* Ninth graders in the affected middle schools will attend five high schools offering grades 9 through 12. All 20 high schools will be four-year schools by 1985.

* School Superintendent Feeney has named a panel to develop a plan for a special visual and performing arts program to take advantage of the new auditorium to be opened at Suitland High School next year. The program, like the unique science and technology center at Eleanor Roosevelt High School, would selectively draw talented students from throughout the county.

The one major improvement the system had hoped to make -- a reduction in elementary class sizes that would cost $2.5 million -- was cut by two-thirds in a budget tradeoff to fund a wage increase for the county's 6,800 teachers. Since class size reduction was an important concern of the teachers in negotiation, it became linked to the teachers' pay raise in the bargaining.

Assuming that the teachers will accept a pending contract offer calling for a 9 percent raise this year and up to 7.7 percent next year, the board will have funds to add only 60 new classroom teachers instead of a planned 182.

"The teachers did not put themselves in that position, the governing authorities did," said teachers union president John Sisson. "It's a 'Catch-22' position -- your family starves or you get stuck with a larger class. I think it's sad."

School officials also are keeping their fingers crossed that the teachers will approve the two-year contract, thus removing the lingering threat of a strike. The mail-in ballots will not be counted until next Thursday.

Another potentially serious threat hanging over the system is the re-opening of the 1972 desegregation suit that sent school buses rolling and temperatures to the boiling point in 1973. Last week the school board turned down a proposed consent agreement from lawyers for the national NAACP. The NAACP maintains that the system is as racially isolated as it was in 1972 and shows a pattern of discrimination in teacher assignment and student discipline.

While a suit is not likely to significantly affect education this year, it could force changes in the school closing plan. It also would tie up school lawyer Paul Nussbaum in costly litigation.

Meanwhile, due to Reagan administration budget cuts in federal subsidies for school nutrition programs, the price of student lunches will be higher. Elementary lunches will go from 70 cents to 90 cents, secondary school lunches from 75 cents to 95 cents and the familiar half pint of milk will go from 15 cents to 25 cents. The price rise will keep the cost of lunch higher in Prince George's than in Montgomery County.

Federal budget cuts also have eliminated the $933,000 in last year's budget that would have helped to alleviate problems of integrated education. The cut will affect special reading programs and extra staffing in schools with high minority populations, although all teachers affected have been retained by the school system.

Despite the year-long struggles with the teachers' contract, the tight budget and the NAACP threat, school board chair Jo Ann Bell remains an irrepressible booster of the metropolitan area's second largest and most racially and economically diverse school system.

"One of the neat things about this county is that everybody gets their shot. But the bottom line always is what is best for the students," Bell said. Nevertheless, perhaps in preparation for the budget struggle that will begin anew in four months, she warned:

"I think over the years we've made do and done it superbly, but you can't do that for but so long. We don't have the same amount of paper anymore, we don't have the same amount of overhead projectors anymore. It's a very technical world out there and if you want us to keep up you're going to have to do something about it."