Pressing play — stories about children and how recreation is a form of creation. Kurt Andersen takes a field trip to Governors Island with design critic Alexandra Lange to learn about the history of playgrounds — and see some extraordinary slides. Paola Antonelli tells us the humble beginnings of the Frisbee, its origins being in a pie-baking company whose pie plates, college students discovered, were impressively aerodynamic. Producer Jessica Benko talks to an 8-year-old about her imaginary friends, and to a psychology professor about how those invented characters reflect well on the imagination of the kids who conjure them. And we examine the surprising — and controversial — history of Barbie, who has become an obsession both for the kids who play with her and the artists who feature the dolls in their work.