This manual, included in the online exhibition Invention at Play, from the Lemelson Center, will provide an array of activities, resources, and approaches that will underscore the role of play in the inventive spirit in all of us. Through play we develop certain "habits of mind" - curiosity, persistence, imagination, communication, problem solving - as well as skills in manipulating and understanding the properties of the material world. Research has shown that this array of abilities has been and continues to be an important part of the inventor's tool chest.