School boards in Montgomery and Arlington counties voted last night to close schools in the face of shrinking enrollments, while the board in Fairfax County -- where more closings are proposed -- held a public hearing on the issue.

In Montgomery, the Board of Education voted to close five schools: Grosvenor Elementary School in Bethesda, Larchmont Elementary in Kensington, English Manor Elementary in Rockville next fall, North Bethesda Junior High and Northlake Elementary in Rockville in 1981.

On Wednesday night the board had voted to close a sixth school, Randolph Junior High in Rockville.

Last night's board meeting was an emotional one. The decision to close Grosvenor Elementary drew an angry denunciation from one parent and bitter calls for a "referendum" to elect a new school board.

One North Bethesda parent, William O'Reilly, said his group, the Maryland Federation of Catholic Laity, would seek legislation to break up the Montgomery board into three districts. "We're willing to keep our schools open," he said. "If they tell us how much additional tax it would take, we'd vote for it."

The board took no further action to resolve serious underenrollment problems in the Silver Spring area. On Wednesday night, it decided by a 4-to-3 vote to keep Sligo Junior High open, but took no action on a proposal to close Eastern Junior High. This left the Silver Spring problem unresolved.

That problem may become more serious in view of the board's decision last night to add the ninth grade to Northwood High School in west Silver Spring. This will force both Eastern and Sligo to give up some of their ninth grade students. The underenrollment problem is particularly severe at Eastern, and Acting School Superintendent Edward Andrews said last night, "We'll have to figure out some way to help Eastern."

The board also decided to add the ninth grade to Robert E. Peary High in Rockville. ARLINGTON

In Arlington, the school board unanimously rejected the recommendation of Superintendent Larry Cuban by voting to close one elementary school, Stonewall Jackson, instead of two at the end of this school year.

Cuban had recommended closing both Jackson and Ashlawn elementaries because of declining enrollment. Over the last 10 years, county school enrollment has fallen from 13,775 to 8,825. School officials estimate a 4 to 5 percent annual decline continuing until 1984.

School board members said updated enrollment projections indicated a slower decline. Members also cited the completion of Arlington's four new Metro stops and the soon-to-be-completed I-66 highway system as future developemnts that could change enrollment projections.

Arlington will be in great flux in the next few years," said board member Torill B. Floyd. "We would sit tight until the dust has settled."

All five board members listed Jackson Elementary at 850 N. George Mason Dr. as their first choice for closing because of the school's poor facilities. Jackson was built in 1926 and has had four additions.

"I think it stinks," said John Gorman, father of two children now attending Jackson, after the vote was made. "Jackson doesn't have an enrollment problem. Ashlawn and McKinley have the enrollment problem. They're sacrificing Jackson to keep them open."

Cuban said, following the board's action: "The issue of consolidating schools will arise next year and the year after. The situation is just not going to go away." FAIRFAX

Only a handful of disgruntled parents turned up at a public hearing before the Fairfax County School Board last night, and only two addressed the board as the long process of choosing which schools to close there formally began.

Fairfax school administrators announced last week they were studying 29 elementary schools with the intentionof closing several at the end of this school year. A number of studies and reports will be made before final recommendations are submitted to the school board.