The aim of this study is to investigate and compare level of understanding of eighth-grade students and student teachers in their final year in the science education department related to concepts of solution, gas, and chemical change. A qualitative and quantitative methodology was used for this investigation. Open-ended questions and group discussion methods were used for data collection. Moreover, to examine how students visualize these concepts, students were asked to make drawings. The questions were administered to 50 students in Grade 8 and 50 student teachers in the science education department. Group discussions were conducted with 6 students and 6 student teachers. There were surprisingly similar alternative conceptions by both the students and the student teachers despite more instruction on these topics in the education of the student teachers. Based on the results, some suggestions are presented. © 2005 Wiley Periodicals, Inc. J Res Sci Teach