Today's hottest toys, according to a saleswoman at F.A.O. Schwartz, an upscale toy store, are "Guk, Teenage Mutant Ninja Turtles and anything Nintendo."

Guk? The manufacturer claims that Guk "teases the touch and tickles the imagination." The saleswoman explains: "It's a substance that's solid when it's being played with - when pressure is applied to it - but liquid when it's left alone."The top-selling toys 35 or 40 years ago were not so complicated. Hot items included Lone Ranger gun-and-holster sets, Lassie wallets and anything related to frontiersman Davy Crockett. But whatever the generation, the relationship between children and their toys is extraordinary, in many ways revealing more about adult society than about children.

From a child's point of view, a toy is something to play with, but people who study popular culture can learn a great deal from looking at the playthings that have entranced children through the years.

An exhibition at the Smithsonian's National Museum of American History in Washington, D.C., documents childhood during the Cold War - an era that produced the largest generation of children ever born in American history. The exhibit, "This Is Your Childhood, Charlie Brown: Children and American Culture, 1945-1968," examines the toys, television programs and consumer products aimed at young people of that time.

Characters from the comic strip "Peanuts," created by Charles M. Schultz in 1950, help illustrate the history of childhood in this era. One of the most successful comics of its time, the "Peanuts" strip reflected many of the concerns facing American families: the threat of nuclear war and communism, the pressure to conform and succeed, and the dream of prosperity.

Exhibition curator Charles McGovern says that the soaring birth rate made postwar America a child-centered culture. "Two concerns dominated discussions about children: the need to train them to conform to social norms and group standards, and the need to provide them with a strong sense of security."

The importance of family life in ensuring continued social harmony and American democracy during the baby boom led to greater emphasis on teaching boys and girls proper and distinct roles, McGovern says. Fears of communism made any social deviance suspect, he adds, and parents faced unusually strong pressure to teach children strict conformity to social norms.

"Toys were instruments of parents' concerns as well as vehicles of release for children," McGovern points out. Girls received specialized lessons about appropriate feminine behavior in this period. "Toys and play for girls taught them to cultivate their physical beauty and social skills, to prepare for marriage and to be `pretty like mommy.' " Toys included perennial favorites such as baby dolls and dolly high chairs, as well as the Mystery Date game and the Kenner Easy-Bake Oven. Playing dress up - especially in Annie Oakley outfits - was always fun.

Boys, meanwhile, were encouraged to be active and competitive. Their toys often involved machinery and science to train them to take their places in the work force. Busy Boy Tool Chests and Norelco electronic kits were all the rage.

McGovern believes that though the postwar years are often mythologized as carefree and innocent, they were, in fact, an anxious and turbulent period for American families. "Happy suburbanites and the threat of nuclear war lived side by side," he says.

Indeed, Cold War ideology shaped children's play as it centered around the Wild West and outer space. "In both locales, the `good guys' faced an enemy from an outlaw or foreign people whose entire culture - like that of the Soviets - was fundamentally opposed to their own," McGovern points out. "Children's games, toys and popular stories of heroes and heroines often reinforced such stark contrasts and taught children that those who do not share their way of life were the enemy."

"Toys can be influential," McGovern says. Take the Gilbert Atomic Energy Lab, a nuclear physics set for the "junior scientist" who could "perform over 150 exciting experiments."

"When the U.S. government dropped the atomic bomb on Hiroshima," he says, "Americans became keenly aware of the threats of nuclear warfare. It was not long after that the Gilbert Energy Lab was made available. Its intention was to dispel fears about atomic energy by `domesticating' it."

Popular board games of the day included "Life," "Traffic" and the stock-market game "Rich Uncle." Unlike work in real life, these and other games valued chance, not skill, to bring the player success and wealth. Many popular board games were symbolic journeys to success. The object of "Traffic" was a popular dream in American postwar culture: to win a Cadillac.

Spending and consuming became important aspects of childhood during the postwar years. That generation made up the greatest potential market in American history, and manufacturers and advertisers sought to win their allegiance in childhood. "Postwar children were taught to be avid consumers," McGovern says. "Parents, corporations and schools taught children the American way of consumption through playthings, stories and lessons."

Barbie was the most popular doll of the day. More than any other toy, Barbie encouraged little girls to be active consumers by collecting a seemingly endless array of accessories sold for her.

Even bubble gum cards carried the message of consumerism by teaching kids the skill of amassing many items of the same kind. Whereas at least a generation before had collected baseball cards, children in the postwar era could collect public figures, television heroes, fantasy characters, musicians and, of course, athletes on gum cards.

Postwar children were the first generation raised with television, and it became a major force in their upbringing. "Television taught children powerful lessons - conformity, respect for social authority, and, above all, the importance of consumption," McGovern says.

The popularity of the Walt Disney TV show "Davy Crockett" revealed that children could be sold products that occupied every waking hour of their days. Many children had the Davy Crockett coonskin cap, cereal bowl, water glass and phonograph record. Other programs that spawned consumer items included "Lassie" and the kindergarten show "Romper Room," which promoted a broomstick horse and various books.

"Today, the lessons coming from toys are different than they were 45 years ago because we have different concerns," McGovern says. "We're not in a Cold War, but we are trying to teach children about racial equality and the environment."

No matter what a parent's concerns are, there are toys that children will always love, staples in many toy chests. McGovern cites some of the all-time favorites of the last 40 years: baby dolls, Matchbox cars, the Hula-Hoop, the Slinky, the Frisbee and the Etch-a-Sketch. Children do not demand much from these toys. "Kids find life in everything," McGovern points out. All that's asked of a Teddy Bear, for instance, is that it be a companion.

Time will tell, however, if Guk, Teenage Mutant Ninja Turtles and Nintendo will endure.