The modern playground is a reflection of the restrictive attitudes of parents and community planners who have limited children's access to natural environments and their opportunities for unstructured play, according to Mark Francis, a professor of landscape architecture at UC Davis. Francis, whose upcoming book is titled "Childhood of Imprisonment: Restoring Childhood in America," fears that many children are being denied a natural childhood. He says, "Children have been imprisoned by structured lives imposed by parents and institutions, and a lack of contact with nature." He believes natural, unstructured places offer the best opportunities for spontaneous, intuitive play and creative learning, but modern suburban designs have removed nearly all natural areas, and many parents organize their children's time to the point that they lead highly structured, adult-like lives. Francis advocates restoring and preserving natural and underdesigned areas in public places, such as school playgrounds, city parks and greenways, and changing the attitudes of parents, teachers and designers. He also favors involving children in landscape design and planning decisions, noting that studies, including his own, show that adults prefer an open, manicured landscape where they can monitor their children's activities. Kids, meanwhile, like hiding places, such as unmown areas and clusters of trees and shrubs.