摘要:Abstract The purpose of this study was to explore pre-service science teachers' perceptions of scientific fact, hypothesis, theory, and law and understand how these perceptions change at the beginning and end of teaching process. The study was conducted with a total of 35 pre-service teachers who entered the science education department in 2006 and graduated from the same department in 2010 year. For this purpose, it was asked pre-service teachers what they know about hypothesis, theory, law and scientific fact and their perceptions of these concepts. Results indicated that pre-service teachers have misconceptions. Results also indicated that pre-service teachers' misconceptions decreased when they graduated. Furthermore, it was found that there is a significantly difference between students' academic achievement and the levels of perceptions of the concepts. Pre-service science teachers' have been identified to improvement in this situation that perception of misconceptions about theory, laws, hypotheses, and scientific fact undergraduate education from high school. Keywords: Nature of science, scientific fact, hypotheses, theory, law.