Based on the Kellian view of constructive alternativism (that the meanings of any idea are not fixed, but vary from individual to individual), this paper describes a technique for exploring school children's conceptions of common physical phenomena to allow science educators (1) to appreciate the alternative conceptions of their students and (2) to provide learning experiences whereby these conceptions might be modified. The Interview-about-Instances (IAI) method is a technique for eliciting these meanings. The IAI technique consists of tape-recorded dyadic discussions with a student, using a deck of cards (concerned with the applications of one word), as a focus. The method elicits a range of responses revealing the breadth and manner of use of the chosen word. Designing a deck of IAI cards, the process of elicitation, and the transcription of interviews are discussed. Outcomes of the technique, illustrated for the concept "force," are presented. (PN)