The purpose of this study was to examine how prospective middle school science teachers understood and identified types of scientific knowledge in a presented vignette. Also, their definitions and views of the relationships between types of scientific knowledge (i.e. scientific facts, concepts, generalizations, theories, and scientific laws) were investigated through open-ended questions. Additionally, participants were given the Nature of Scientific Knowledge Scale (NSKS) after they responded the open-ended questions. Therefore both qualitative and quantitative data were obtained about their understandings and views about scientific knowledge. Thirty six participants responded the questionnaires at the end of the spring semester 2005. During this semester participants were in their junior year and enrolled in a 'history and nature of science' course in which 16th and 17th century scientific revolution and the historical background leading to those developments were discussed. Participants received no specific instruction about the definitions of types of scientific knowledge like theories and laws. Analysis of the quantitative data obtained via NSKS show that participants hold a view favoring the tentativeness of scientific knowledge and mostly appreciate the developmental nature of science. While, on the other hand, analysis of the qualitative data obtained through the open-ended questions illustrate that participants hold a stepwise development view in science assigning the tentativeness in science to theories and lower steps. Overwhelmingly they emphasize that scientific laws reflect proven truth and in a sense absolute. These findings show the usefulness of utilizing appropriate vignettes for probing views. The results are disscussed in the light of existing literature and implications are provided.