Scheduling playtime in 45-minute increments seems strict, but the New York Hall of Science playground for preschoolers, featured in Landscape Architecture (article not available online), demands it. So families and school groups dutifully follow the rules and sign up. The playground was originally designed for teenagers, but the recently added preschool portion of the 10-year-old recreation area lets four-year-olds learn through play about fluid mechanics, acoustics, hydrology, and color theory. The preschool area is a garden-like environment of trees, shrubs, flowers, and grasses that transitions gently into the park beyond. A wavy line of benches provides a permeable barrier and parental vantage point between the areas for younger and older children. Unlike most play spaces, the Science Playground aims to inspire children, not pacify them with pre-made parts that minimize litigation fears. But freedom comes at a cost, as the park comes with an entrance fee, on top of the fee that families must pay to enter the museum.