Participants in this study were total 87 of male and female undergraduate students enrolled in introductory chemistry courses, from the two classes of the same teacher in Atatu ¨rk University, in Turkey. One class was randomly assigned to the experimental group (n= 46) while the other formed the control group (n= 41). While the experimental group was taught with the conceptual change instruction, the control group used traditional instruction. During a four-week period, each group received an equal amount of instructional time and was provided with the same materials and assignments, apart from the conceptual change text in the experimental group. Duration of the lessons was four 50-min periods and the language of the instruction and the language of the text used for both the experimental and control classes was Turkish. The method used in this study will be described in
detail, later.