When the owner of the Virginia McMartin Pre-School and six of her teachers were indicted on felony child-molestation charges last spring, the case seemed to switch on a floodlight, illuminating the sexual abuse of children as a national problem of epidemic proportion.

Today, nearly a year later, a child took the witness stand for the first time in the McMartin case.

The boy, who attended the Manhattan Beach nursery school several years ago, told of "naked games" played there. At the request of Deputy District Attorney Glenn Stevens, the 7-year-old witness, identified as John Doe No. 7, pointed at some of the defendants and said they would "touch us" during the games.

The child was the first of 41 youngsters scheduled to testify in a preliminary hearing for the defendants: Virginia McMcartin, 77; her daughter, Peggy McMartin Buckey, 58; two grandchildren, Peggy Ann Buckey, 28, and Raymond Buckey, 26; and former teachers Betty Raidor, 65, Mary Ann Jackson, 57, and Babette Spitler, 36.

The seven are charged with a total of 207 counts of rape, sodomy and other abuses, and with conspiracy.

Psychologists have testified that the number of children molested at the school may approach 400. Doctors said that 37 of the 41 expected to testify during the pretrial hearing had been molested; the other four had not been examined.

The pretrial hearing began nearly six months ago. For much of the time, parents, psychologists, attorneys and the judge have wrangled over the conditions under which the children will testify.

One mother said in an interview last week that she is not certain her daughter will take the stand. "All we can do is wait until the day she's supposed to testify and see how she feels about it," the woman said.

She said that some days her daughter seems eager to testify, but that recently, while viewing a news report about the defendants, the girl covered her eyes and turned from the television set, telling her mother, "I don't want to see those guys."

The girl is under the care of a psychologist, and her mother said the dilemma is this: "The psychologist said that testifying in an open courtroom could set her back a full year in therapy. But we want those people prosecuted."

The children are testifying in a closed courtroom before the judge, defendants, attorneys and their staffs. Reporters and spectators may watch the proceedings on two TV monitors in an adjacent room.

Municipal Court Judge Aviva K. Bobb shut off the cameras at some points today, deleting testimony she did not want broadcast, such as the first witness' name.

Some parents whose children attended the McMartin school, which was closed by the state last year, are seeking quick passage of a bill that would allow youngsters to testify and be cross-examined via closed-circuit TV. The bill was approved today by the state Senate Judiciary Committee.

Before the young witness was sworn in today, Bobb introduced him to the marshals present, saying, "They are responsible for the safety of everyone in the courtroom." She also told him that one marshal "is specifically responsible for your safety."

Prosecutors have alleged that the defendants intimidated their victims with threats to kill them and their parents and blow up their houses. Prosecutors also claimed that the defendants backed up their threats by killing animals in front of the children.

In answer to Stevens' questions, today's first witness said he knew the difference between the truth and a lie, and that "you get in trouble" for telling a lie.

He then described some of the "naked games" he allegedly played under the direction of teachers at the McMartin school.

There was "Cowboys and Indians": "We were cowboys. The teachers were Indians. They would get us, capture us, then they would take us, put us in a jail, and they'd touch us."

"Where did they touch you?" Stevens asked.

"On the penis."

And the "Alligator Game": "We'd take off our clothes on the floor and crawl around, and while we were on the floor, they'd touch us."

In the "Naked Movie Star Game," the boy said he would "take off my clothes and do tricks, and they would take pictures of us." No such photos have been found.

As the testimony progressed, the youngster seemed increasingly to answer questions with "I don't remember," especially when asked who had made him do something or who had touched him.