Charles P. Whalen, a former Arlington teacher's aide, wrestling coach and boy scout leader, pleaded guilty yesterday to one count of sexual battery of a juvenile and received a 12-month suspended sentence.

Whalen, 38, of 4923 Beauregard St. in Alexandria, was charged in September with aggravated sexual battery of a 14-year-old boy. The incident, according to court records, took place in November 1983.

Whalen also had been charged with one count of sodomy in a 1979 incident involving a 16-year-old boy. Prosecutors dropped the sodomy charge, and in a closed hearing yesterday before Juvenile and Domestic Relations Judge Berton V. Kramer, Whalen pleaded guilty to the lesser charge of sexual battery.

"The reason we did it negotiated the plea agreement is because of the victims in these two cases," said Assistant Commonwealth's Attorney Liam O'Grady. "We spoke to them and their families; the only way they would agree to prosecute was if they never had to testify in open court.

"Our main objective all along was just to get a conviction on a sexual offense," he said.

Whalen had worked since September 1977 as a teacher's aide and resource assistant at Wakefield High School. He also led a local boy scout troop, coached wrestling teams and choreographed school dramatic productions. The School Board voted unanimously Sept. 19 to fire him.

Superintendent Arthur W. Gosling said yesterday that he considers Whalen's dismissal from the school system permanent. "We have no plans to rehire him," he said.

Gosling added that this incident, as well as several similar cases in neighboring school jurisdictions, has prompted more careful screening of job candidates.

"We have tightened up our own background checking now. We're insisting on more thorough checks into employer references. You can get sloppy about it. . . These cases have made us sharper in looking at those sorts of things."

The case involving Whalen surfaced when Arlington school officials placed him on leave without pay Aug. 28 after police told them investigators had seized 8 to 10 cartons of allegedly pornographic materials depicting children during a search of his apartment.

On Sept. 11, Whalen surrendered to Arlington police and was charged with aggravated sexual battery. Several weeks later, he was charged with sodomy in an incident that allegedly occurred Dec. 8, 1979.

Police said the youth involved in the alleged sodomy had met Whalen through school activities.