A cross-section study of the understanding of chemical kinetics among Turkish secondary and undergraduate students

The purpose of this study is to evaluate secondary school and undergraduate students' conceptual understandings of chemical kinetics in the light of the aims of the Turkish chemistry curriculum. This purpose is addressed through a cross-sectional design. So as to identify the intended development of the subject of chemical kinetics within the school and university courses, the science curriculum, chemistry textbooks and students' notes were analysed and interviews were conducted with teachers/lecturers who had taught chemical kinetics unit at the participating institutions. Based on a conceptual analysis of the domain, key scientific ideas in chemical kinetics were identified and a number of open-ended diagnostic questions were designed to provide contexts through which students' understanding about each of the key scientific idea could be investigated. The study is based mainly upon the written responses given by 191 upper secondary school students (ages 15-16) and pre-service chemistry teachers (age 17+) to a series of written tasks involving concepts and phenomena in chemical kinetics. A sub-sample of the students was also interviewed in order to obtain further information regarding their ideas about chemical kinetics. Conceptual analysis of the domain suggested that the rates of chemical reactions can be explained by a qualitative approach (Particulate Modelling) and may also be understood in terms of a quantitative approach (Mathematical Modelling): ultimately these two approaches are amalgamated in some levels. In order to achieve a full scientific understanding, students need to have some understanding of several modes of modelling. However, this is not often reflected in the curriculum. In some areas of the domain there is a mismatch between the objectives of the curriculum teaching and the outcomes of the curriculum. In a broad sense, the students following the curriculum made progress from secondary through university level. This progression was different in different areas of chemical kinetics. (1) Changes in the nature of explanations offered by students and (2) changes in the conceptual content of explanations offered by students were identified. I found progression in the forms of justification used across the educational level, with school students tending to justify propositions by simple prototypical examples, or by drawing upon taken for granted everyday knowledge. By contrast, undergraduates were more likely to provide explanations based upon theoretical models and entities within established chemical ideas. Though both school and undergraduate students were more likely to give a correct answer to how a change in the reaction conditions (e.g. increasing the initial concentrations of reactants) would influence the reaction rates, yet they had difficulties in providing explanations about the dynamic nature of the reaction system. The results indicated that several conceptual difficulties exhibited by the school students persisted in the undergraduates. Furthermore, the results suggest that students' lack of understanding in thermodynamics and chemical equilibrium significantly influences their ideas about chemical kinetics. Some possible implications for planning the curriculum and teaching are proposed in the light of the results of the study. Avenues for further research are also identified. The findings can be drawn upon by teachers, lecturers, textbook writers, researchers, and curriculum designers in planning more effective teaching activities .