Physics teachers use experimental devices to show students how scientific concepts, principles, and laws are applied to understand the real world. This paper studies question generation of secondary and under-graduate university students when they are confronted with experimental devices in different but usual teaching situations: reading about devices while studying still images or diagrams, watching an experimental demonstration, and handling the devices in the laboratory. The influence of the prior scientific knowledge on the questions asked is also analysed. Inquiry learning environments, involving lab projects, seemed to stimulate more inferences addressed to causality when students tried to build mental models, whereas reading about devices with the help of still images stimulate more descriptive inferences and inhibited predictive ones.