This paper reports on methods used to probe student understandings of optical fibers and total internal reflection (TIR). The study was conducted as part of the expansion and improvement of web-based materials for an innovative introductory physics course. Initially, we conducted face-to-face Piaget-style interviews with a convenience sample. Our next step was to interview students taking the course at Rensselaer. Physical limitations necessitated that this be done from a distance, so we conducted "e-interviews" using a Chat Room. In this paper we focus on the e-interview experience, discussing similarities to and differences from the traditional face-to-face approach. In the process, we address how each method informs us about students' activation of prior experiences in making sense of unfamiliar phenomena (e.g., "transfer of learning").