The purpose of this study was to investigate prospective chemistry teachers' knowledge about instructional strategies, one component of pedagogical content knowledge about introducing particulate theory, as well as sources of this knowledge. Twenty-two prospective chemistry teachers participated in the study. Data were collected by the means of a vignette, semistructured interviews, and lesson plans. Analysis showed that concrete objects, computer animations, and expository teaching were the preferred teaching techniques by prospective teachers. Several issues, such as general pedagogical knowledge, subject matter knowledge, and knowledge about students' difficulties, were found to be the main factors for choosing a teaching strategy to make an introduction to particles.