Parents obsess over their children’s playdates, kindergarten curriculum, and every bump and bruise, but the toys, classrooms, playgrounds, and neighborhoods little ones engage with are just as important. These objects and spaces encode decades, even centuries of changing ideas about what makes for good child-rearing-and what does not. Do you choose wooden toys, or plastic, or, increasingly, digital? What do youngsters lose when seesaws are deemed too dangerous and slides are designed primarily for safety? How can the built environment help children cultivate independence? In these debates, parents, educators, and kids themselves are often caught in the middle.