In this paper we describe a qualitative study of the role of the physical models in transferring physics ideas to understanding positron emission tomography technology. Sixteen students enrolled in an introductory level physics class individually participated in two sessions of a teaching experiment. In this study we noted that many students used reasoning from prior experiences in inappropriate ways. A result from this study is that physical models are effective in triggering appropriate transfer provided that the activities using the models are introduced in the right sequence. Given the appropriate sequencing of the activities, we find that the transfer of abstract ideas is facilitated through interactive learning with the aid of physical models. Three different types of non-scaffolded transfer have been identified: spontaneous, semi-spontaneous and non-spontaneous transfer.