When you walk around a science center and see visitors engaging with interactive exhibits, you imagine that a lot of learning is going on. What unique learning opportunities do interactive exhibits offer? What is the significance of learning by doing? What does the visitor gain from acting rather than just watching? And how can you measure how what people do affects their learning experience? Traditionally, we have used surveys to determine if visitors have understood the phenomenon, or if they have become more interested in the topic. But asking verbal questions may not always be the most suitable way to capture if and how learning takes place during physical interactions. In this REV group workshop, we will discuss how we can use observations to study how and what type of learning takes place when visitors engage in physical interaction with exhibits. We will start looking at this from a more theoretical standpoint and apply that understanding in thinking about appropriate methods.