Gene Wenner wants to add an "M" to the three "R's."

"No one disputes the need for the three 'R's,' says the 48-year-old musician, composer and educator. "But alone they can make Jack and Jill very dull and turned-off students.

"A good music program -- a school chorus, band or orchestra -- could be the thing that motivates a kid to stay in school. Music complements and reinforces academic skills. It's a place to practice sharing and group work, even learn about history and other cultures. And it's fun."

As president of the American Music Conference (AMC) -- the music industry's organization to promote music in the home, school and community -- Wenner is encouraged by the growing numbers of people who are learning to play instruments.

"About 50 million Americans -- one out of every four -- say they can play a musical instrument," he says, citing a recent Gallup survey commissioned by AMC. "In 1970 it was one out of six. The growth comes partly from increased leisure time and because gas prices make us want entertainment close to home.

"Families with above-average incomes and individuals with a colllege, or at least a high-school education are most likely to pursue music. Women make up more than half of all amateurs."

Although Wenner admits that inflation and "Proposition 13 fever" are straining school budgets, he says music programs are alive and well in most American schools.

"But the schools can't do it alone. Parental involvement is important if a child wants to learn to play an instrument. Motivation is crucial to success, and parents can be crucial to motivation."

It doesn't matter if your child doesn't appear musical, says Wenner, who eschews the "you-either-have-it-or-you-don't" theory of talent. "If someone wants to play an instrument badly enough, the combination of desire, time and energy will make them successful."

It's never too early to introduce a child to music, he claims. Pre-schoolers can attend kiddie concerts, listen to records like "Peter and the Wolf" and play "pre-band" instruments such as a wooden flute, recorder or toy drum.

Regarding some teaching techniques -- like the Suzuki method for string instruments -- which advocate instruction as early as age 2, Wenner says, "They require a great deal of parental participation." For most children private lessons usually begin in the third or fourth grade.

The choice of instrument depends on many variables. "Look at the physical requirements -- you're obviously not going to start a 6-year-old on a tuba.

"Each of the major instrument groups requires a particular skill. String instruments require a good hand-eye coordination -- and most come in child-size versions. Wind instruments need a combination of mouth control and dexterity. v

The lip is important in brass instruments. And coordinaiton and good sense of rhythm is important for percussion.

"Consider the goal. Do they want to play in the marching band, a string quartet, a rock group or accompany their own singing?"

(The top 10 instruments in order of popularity: piano, guitar, organ, clarinet, drums, fluts, trumpet, violin, harmonica, and saxophone.)

Three good sources of information about music teachers are the parents of children who play instruments, the public-school music teacher and the manager of a local music store.

"A parent," says Wenner, " can help the teacher by relating some of the child's nature, what he or she likes and doesn't like. Be interested in how your child is doing. Listen to them play and talk about the instrument."

If it fits your home and life style, encourage the child to practice in the living room rather than shut off in a another room. "That way music is just part of the family. But if they'd rather practice in private, that's okay, too.

"Set up a specific time each day as practice time. Don't deliberately set a time against another desired activitiy, like when all the other kids are outside playing kickball. But even if a child has to get up a half-hour early, practice time should be a part of their routine."

The child's initial excitment about playing may wane when the novelty turns out to be hard work. "Teachers know that's going to happen, but most parents don't. They should provide some kind of reinforcement at that time to get the child over the hump."

The best reinforcement, says Wenner, whose son is a drummer and daughter a dancer, "is the joy and sense of accomplishment you get from sharing your music with others. Openly encourage (but don't force) children to play for relatives and friends in the home.

"Seek out a group, band or choir, that they can participate in. Music is best when it's shared."