Think back to your first school play. Were you the star ? Be honest. Were you the star, or did they ask you to play:

A. A rock.

B. A crowd scene. ". . . Johnny, you are the crowd. Go over to the corner and mill about."

C. A passerby. ". . .Good passing by, Sylvia. Now just keep going off the stage and back to your seat."

Another question. When you hear the words "participation theater," what do you think of?

1. Performers yelling at the audience.

2. Audience yelling at the performers.

3. Everyone getting naked and eating oranges.

Well, as an ex-A B C who thought participation theater was all of the above, I have news for you. It doesn't have to be that way.

Enter, stage right, two Arlingtonians, Fuller and Murphy (Kathy Fuller, drama teacher with the Arlington Recreation Department; Donn Murphy, head of the Georgetown University drama department), co-directors of InterPlay Productions, a unique theater participation company.

They're out at Wolf Trap Farm park in the Meadow Tent doing two free performances a day of "The Curious Computer From Planet Zee." The "actors" are the children who begin as part of the audience and wind up as stars of the show. Fuller, Murphy and the Troupers seem to be having so much fun they entice even the most stage-shy child into participating - dancing the bunny hop, helping Wolf Trap Jack "film" a movie, saving Princess Lovely from the clutches of Dark Traitor and doing a "kick" that would put the Rockettes to shame.

The play that started the Fuller and Murphy partnership was "Creation of the World," adapted for children through a grant from the Humanities Project as part of an Arts to the Community Program in Virginia. They trained teenagers ("troupers") to help the children follow the taped instructions and guide them through the various movements. For the past four years they've been at Wolf Trap as part of the National Park Service's Summer Enrichment Program.

One of their early performances at Wolf Trap involved an unexpected visit from a group of severely handicapped children. There was no time to change the tape, which says, "You are a healthy, young tree. Plant your strong roots in the ground." The children had their limbs in traction, or worse, but somehow they managed to respond to the instructions. When movement was impossible, the troupers would gently guide or carry a child from place to place.

"It was absolutely incredible to see what those kids could do," said Kathy. "They put everything they had into it. One boy said to me at the end, 'I understand, I understand."

The Fuller and Murphy principle is that participation theater should be gentle, not threatening or embarrasing.

"For example," said Kathy, "when we first bagan with groups of very young children we would ask them to take the hand of the friend next to them. To the first graders in the group this meant running frantically all over the tent to search for a familiar face and the hand that went with it."

Last year at Wolf Trap, Fuller and Murphy presented their first group play written specifically for children. It was a painless, funny introduction to ballet, mime and music, called "Happy Landings."

"We didn't want to do a 'Hi-kids-this-is-puppet-Judy-and-you're-all-going-to-learn-something-today,' says Kathy in a very authentic Puppet Judy voice. "I hate that approach and kids hate taking culture vitamins when they've come to have a good time."

"Happy Landings" was an imaginary airplane trip with the troupers as stewards and stewardess and Fuller and Murphy as co-pilots. The "plane" landed at different countries where the group visited a ballet class and took lessons from the world's tallest ballerina (a trouper sitting on another trouper's shoulders). They observed a mime class, became spear-carriers in the opera, joined a circus, danced in a Greek village dance, participated in a wedding and finally landed at home to a rousing welcome, complete with cheerleaders.

Without being beaten over the head with the fact, the boys in the group discovered that ballet takes strength and coordination and is not for "sissies." In the same vein Fuller and Murphy were careful to use boys as well as girls for cheerleaders, and to use girls as co-pilots and plane technicians.

"However," laughed Murphy, "I think what the kids enjoyed the most was getting to pantomime using the throw-up bags and life-preservers. You can imagine the embellishments they added to that little ritual of airplane travel."

"Happy Landings" was not as internal an experience as the "Creation" plays; for that reason it was easier for children to participate as it offered group security to the child who wants to take part but is shy. "Good participation theater," says Murphy, "gives people an excuse to do what they're dying to do anyway but with a minimum of risk."

Right now you can get over to Wolf Trap and see "The Curious Computer of Planet Zee" with your child taking part, along with a roller-skating mouse, Princess Lovely and Luke Skateboarder on a skateboard built for two, and a slow-motion football game Admission is free but you must have reservations. "Computer Zee" will be at Wolf Trap throughout the summer.

"Come on out and join us," said Murphy. "It's not half as scary as charades."

"That's right," added Kathy. "And it may be the only chance you'll ever get to meet at android."