Sports are among the pleasures of life passed traditionally from father to son, and during a recent game at RFK Stadium the familiar pattern could be seen. There sat a father and son (the boy perhaps 9), one explaining the joys and intricacies of the game to the other.

But it was the boy talking and the father listening. The game was soccer, overwhelmingly popular among children but new to many parents.

Until recent years, most children's sports programs were tailored to fit the dreams of parents, who saw a Pete Rose or a Bob Dandridge in their spindly son, a cheerleader in their chubby daughter. This meant programs almost entirely for boys, with the emphasis on tough competition. Talented boys with the time and desire to practice a lot excelled, and loved it.The rest watched.

Competitive, varsity-type programs are still available, and as popular as ever. But they have been joined by a wave of sports programs for young children that emphasize participation for all, girls included. Many leagues require that each child play half or more of every game.More sports are offered, some generous enough to accomodate the soft and round as well as the hard and lean.

Although coed sports are ideal for the most athletic girls, a rush to compete with boys several years ago backfired, with many girls dropping out because they could not keep up.

"Our organization is encouraging separate teams until we reach a point where girls get the same early treatment as boys," said Helen Knierim, acting executive director of the National Association of Girls and Women in Sports. "Right now, the boys are far ahead."

For children just reaching the age of participation, typically 6 to 8, the choice of sports can be bewildering. Authorities in physical education and recreation say that sports differ markedly in the degree and type of skills required, and even in psychological satisfactions.

The best course, authrities say, is to let your child sample at will, with an occasional parental nudge.

In any sport, choose the coach with care. The athletic thickets abound with lamblike fathers transformed into lions by the coaching mantle. They see themselves as Vince Lombardi, their mission as victory at any cost, and your child as meat for the grinder. It comes out in a game or practice; go watch.

Here and elsewhere, children are voting with their feet for soccer. "Soccer is king," said James Wiltshire, sports coordinator for the Montgomery County Recreation Department.

Soccer provides more action, and requires less skill, than most team sports. Outstanding players excel, as they do in any sport, but mediocre ones get by. Every player except the goalie is in constant motion, and everyone gets to kick the ball. Just as important, a player is rarely put on the spot.

"It's a fast-action game, and you have to really concentrate on someone's performance to notice whether he's good or bad," said Steven W. Barnett, progra, administrator for the National Association for Sport and Physical Education.

It is eye-hand coordination-typically not developed at an early age-that separates good players from bad in base-ball. Throwing, catching and hitting a ball require skill that cannot be picked up overnight.

Howard Hobson, a tall, eternally cheerful man, has run a Bethesda baseball league for sixth and seventh graders since retiring from government work in 1970. He estimates that three of every four batters in his league and a related league for fourth and fifth graders, either walks or strikes out. It is that hard for a child to throw accurately, or to hit a pitched ball.

Uniquely in team sports, the batter in baseball is in the imelight. It is a moment of glory for the skilled, of humiliation for the unskilled. It is just as hard to hide athletic clumsiness in basketball, a fast and exhilarating game that requires speed and coordination of eyes, legs and hands. With only 10 players on the floor, every player is on display.

Not so in football, where everyone watches the backs and only fond parents watch the linemen. But older children learn to take pride in the specialized skills of playing on the line, and a good coach can instill the same pride in young children.

"We try to coach a team spirit, and we encourage some of our best players to be linesmen," said Charles E. Schauss, a hydrologist for the National Weather Service who chairs a football program run by McLean Youth, Inc. "Playing that position, they can become leaders."

To the uninitiated, hockey appears to require extremely refined skills, but in fact it shares some of the egalitarian characteristics of soccer. Both games are fast, with everyone participating, and even at the professional level, control of the puck or ball shifts frequently from one team to the other. If a child fumbles a football, drops a baseball or has the ball stolen from him in bastketball, it looks bad. In hockey or soccer, it can look routine.

Peter D. H. Stockton, an investigator for the House Commerce Committee and a Chevy Chase father of five, has coached children's hockey for years and says it is not a difficult sport to learn.

"The Wheaton Hockey League starts with 5- and 6-years-olds who can't skate, and by the end of the winter they can play a decent game."

Some children with a bent for individual rather than team sports can get both from track, swimming or gymnastics. They rank with soccer, basketball, hockey and the martial arts-boxing, wrestling, karate and judo-as superb conditioners of the legs and lungs. For muscular development of the upper body, the best sports include swimming, gymnastics and the martial arts.

No matter the sport, an important factor in choosing a league is the time involved. Some leagues schedule two or three games a week, and teams practice another day or two. That is ideal for some children, but too much for others.

That kind of reticence, or course, goes against the old varsity ethic, which the Saturday Morning Sports Programs of Arlington County has taken on for 15 years.

Teams play Saturdays only, and every child plays every minute of every game; no substitutes. About 1,000 children, ages 5 through 15, participate in the football and basketball programs, run by parent volunteers. Girls rarely show up for football, but about 15 percent of the basketball players are girls. The Arlington County Recreation Department has copied the format and applied it to baseball.

One result is to show that programs built around participation rather than excellence can work for the traditional "big-three" sports as well as for soccer, hockey and such. One of the program's founders is W. Geregor Macfarlan, a management consultant who coached competitive sports, but noticed that many children were left out.

"Under the old system, 80 percent of the kids who'd like to participate, don't," Macfarlan said. "Maybe they aren't that talented, or they don't want to commit that much time. Besides, a lot of adults who become volunteer coaches think they're in the NFL and the kids suffer.

"We tell the coaches to sit back and relax, put a little fun in their lives. We give the players uniforms and the whole thing-kids like that-but we tell them that the least important thing is the score.

"Just to play is to be successful.The kids love it."