The effect of macro-micro-symbolic teaching on grade ten students' conceptual understanding of chemical reactions

النوع : Mémoire

The purpose of this research is threefold: (1) to identify difficulties that grade ten students in a Lebanese school have that hinder their conceptual understanding at the micro-macro-symbolic interface in chemistry, (2) to investigate the effect of a macro-micro-symbolic teaching approach on students' conceptual understanding of chemical reactions, and (3) to characterize students' conceptual profiles regarding their understanding of chemical reactions in terms of macro, micro, symbolic levels and the relations among them, at the end of the teaching sequence. Forty six tenth graders from two sections in a Lebanese school participated in the study that used a pretest post-test control-group design. The sections were randomly assigned to the experimental and the control conditions during the teaching of the chapter on chemical reactions. The same chemistry teacher taught both groups following a constructivist student-centered approach to learning. Furthermore, instruction in the experimental group was centered on a macro-micro-symbolic teaching approach that (1) focuses on the interplay between the macroscopic, the microscopic and the symbolic levels, (2) integrates the use of various schematic representations, and (3) teaches explicitly with and about models. Data sources for the study included a pretest to identify students' difficulties and two post intervention tasks: a post-test and a concept map (CM) task to compare students' conceptual understanding of chemical reactions. Another data source was the interviews about the CM with eight students purposively selected from both the experimental and control groups to triangulate the findings of other data sources and to characterize students' conceptual profiles. Pretest results indicated that students in the control and experimental groups exhibited difficulties related to the transitions between the macro, micro and symbolic levels. The post-test and the CM task results showed that the experimental group performed significantly higher than the control group and developed more interconnected and sophisticated conceptual profiles. Findings indicated that the macro-micro-symbolic teaching approach enhanced students' conceptual understanding and relational learning of chemical reactions. Besides, the study presented four assertions related to students' conceptual and epistemological thinking about chemical reactions in response to teaching. Implications for instruction, for curriculum development and assessment strategies, and for teacher education programs as well as recommendations for further research are discussed in light of these findings.