The summative evaluation of the National Science Foundation (NSF)-funded Geometry Playground traveling exhibition was a two-year naturalistic study to examine (a) the ways and extent to which the exhibition promoted the practice of spatial reasoning skills, and appreciation for geometry, and (b) its influence on museum professionals' thinking across three venues: the Exploratorium (San Francisco, CA), the Science Museum of Minnesota (St. Paul, MN), and the Don Harrington Discovery Center (Amarillo, TX). The study took place from December 2009 through November 2011 and included five site visits