Main article: History of childhood

American historian Howard Chudacoff has studied the interplay between parental control of toys and games and children's drive for freedom to play. In the colonial era, toys were makeshift and children taught each other very simple games with little adult supervision. The market economy of the 19th century enabled the modern concept of childhood as a distinct, happy life stage. Factory-made dolls and doll houses delighted the girls. Organized sports filtered down from adults and colleges, as boys made good with a bat, a ball and an impromptu playing field. In the 20th century teenagers were increasingly organized into club sports supervised and coached by adults, with swimming taught at summer camps. The New Deal's WPA built thousands of local playgrounds and ball fields, promoting softball especially as a sport for everyone of all ages and sexes, as opposed to increasingly professionalized adult sports. By the 21st century, Chudacoff notes, the old tension between controls and freedom was being played out in cyberspace.[16]