Interactive technologies like multi-touch tables enable museum exhibit designers to support visitors' learning with a wide range of resources (from multimedia to dynamic feedback to the presence of other visitors). Designers must decide, though, how best to align the affordances of these resources with the learning activities they are trying to support . This work examines a multi-touch table exhibit designed to support an activity, tinkering, which has been identified as a form of interaction that may offer special benefits to novices learning about engineering [e.g., 4]. When a learner is tinkering, he or she is engaged in a process of iterative adjustment to a constructed artifact, making use of "just in time" resources and feedback to guide the next steps in their exploration of the problem space. The exhibit studied in this work provided several resources for supporting tinkering, and this paper presents a detailed case showing how these different resources (some technical, some social, and some sociotechnical) were or were not used by learners. A key design goal we identified was the need to transform the tacit engineering practices of visitors into visible engineering performances, such that those performances could serve as "cultural tools"  for mediating the learning of other visitors. Copyright is held by the owner/author(s).