This paper describes our experiences implementing and testing nomadic computing tools at the Exploratorium, an interactive science museum in San Francisco. This is a challenging environment because it is hands-on, boisterous, and makes navigation and visual identification difficult. Therefore, the Exploratorium user experience differs from test environments (e.g. historic houses) used in much previous research. We present a classification of possible tool functionalities. We then describe the two specific prototypes we implemented: an electronic guidebook similar to those deployed by previous research groups and a simpler "Rememberer" tool which allows users to bookmark exhibits and take pictures of their experiences at the exhibits. Results are presented from studies of how people use these tools, as well as from a study of museum visitors without extra technology. Our studies suggest the guidebook is too distracting for many visitors to this environment and that the simpler Rememberer tool better matches their needs. Moreover, our results illustrate the value of early deployment and user testing: our initial experiments with the guidebook led us to the design of Rememberer. 11 Pages