This study examined how urban high school students beliefs about the nature of professional science relate to their beliefs about school science, with particular focus on ideas about the purpose of experimentation and factors influencing knowledge change. A published questionnaire (VNOS, Lederman et al., 2002) was used to assess students’¡Ç beliefs about professional science, and groups of students were interviewed about an artifact they created from a modeling activity. The interview asked about their perceptions of the purpose of the activity, its relation to experimentation to knowledge change, and to professional scientists work. Analytic themes were developed to characterize students’¡Ç responses to interview questions and VNOS items. There are both differences and similarities between students’¡Ç responses in both contexts. Students seemed to recognize their activity as like what scientists would do, and understood it as a modeling task. Yet, students seemed to have few resources to draw upon to consider the nature of experimentation in either their own school work or in professional scientific work...