AdvertisementScientists Say Child's Play Helps Build A Better BrainAugust 06, 2014Jon HamiltonfacebookEmailDeion Jefferson, 10, and Samuel Jefferson, 7, take turns climbing and jumping off a stack of old tires at the Berkeley Adventure Playground in California. The playground is a half-acre park with a junkyard feel where kids are encouraged to "play wild." (David Gilkey/NPR)