The purpose of this study was to assess pre-service science teachers' understanding of science, scientific argumentation and the difference between scientific argumentation and scientific explanation. A total of 40 pre-service science teachers enrolled in a Turkish university completed a five-question questionnaire. The results showed that the majority of participants lacked an adequate understanding of science, scientific argumentation, the difference between scientific explanation and scientific argumentation. Implications of these findings for science teacher education, classroom instruction and assessment were elaborated.