The Effect of laboratory based teaching and traditional based teaching on students' conceptual understanding of chemical equilibrium

by Mathabatha, Stimela Simon.

The purpose of this abstract is to report on the results of the study conducted to identify misconceptions concerning chemical equilibrium concepts, and to investigate the effectiveness of Laboratory Based Teaching (LBT) compared to Traditional Based Teaching (TBT) on University of Limpopo Foundation Year (UNIFY) students' understanding of chemical equilibrium concepts. The subjects of this study consisted of 53 UNIFY students from two chemistry classes. The data were obtained from 27 students receiving LBT and 26 students in the TBT. The validated Misconception Identification Test (MIT) was administered to diagnose students’ misconceptions in different areas of chemical equilibrium. Analysis of the Pre-MIT and open-ended responses revealed widespread misconceptions such as: • Left – and right – sidedness: Students perceive each side of a chemical equation as a separate physical quantity. • The constancy of the equilibrium constant: This includes the ability to judge when and how the chemical equilibrium constant changes. This possible misconception refers to the changes in concentration, pressure and temperature as well as the addition of a catalyst. For example, students fail to grasp the influence of the catalyst on a chemical system, viz., that it has an effect on the reaction rates but not on the equilibrium as such. They perceive the catalysts as leading to a higher yield of the product. • Rate versus extent: Inability to distinguish how fast the reaction proceed (rate) and how far (extent) the reaction goes. • Definition of equilibrium constant expression: Inability to relate the equilibrium concentrations of reactants and products using the equilibrium law. • Misuse of Le Chaterlier’s principle: The application of Le Chaterlier’s type reasoning in inappropriate situations. To address the identified misconceptions, practical based activities on certain aspects of chemical equilibrium were developed as resource material for one group of students (Laboratory Based Teaching - LBT) and similar activities having the same chemistry content consisting of tutorial questions, theoretical background of some aspects and some v University of Pretoria etd – Mathabatha, S S (2005) experiments were used as resource material for the other group (Traditional Based Teaching - TBT). After both instructions, analysis of the Pre MIT and Post MIT results using t – test statistic for each group revealed significant difference between the means of the sample. This implied that both instructions have contributed significantly to the students’ improvement in their misconceptions. Again after both instructions, analysis of the Post MIT results for the two groups using the t-test revealed a significant difference between the two group’s sample means. This implied that the misconceptions in the LBT group were reduced significantly as compared to misconceptions held by students in the TBT group. After both instructions, more students in the LBT group had correct representation of mental models of reactions in equilibrium than the students in the TBT group. Implications for science education classroom practice are also discussed. vi University of Pretoria etd – Mathabatha, S S (2005)