Middle School Students “Making Sense” of Fundamental Concepts in the “Structure of Matter” Unit– the Case of Polymers

Despite the crucial importance of polymers and other high-molecular weight compounds in science, industry and everyday life, the study of this class of compounds receives little attention in the Israeli middle school chemistry curriculum. Polymers do appear in the middle school program as examples in lessons on physical properties of substances such as hardness and elasticity; however, they are not discussed in connection in connection to chemical structure, the subject of "How Compounds and Molecules are Built from Elements." We believe that by exposing students to concepts such as, “Monomer”, “Macromolecule” and “Polymer” as early as the middle school, students may be better prepared for their more detailed study of these concepts later. The research presented here considers the feasibility of designing an instruction unit for teaching high-molecular weight compounds in middle school. Adopting a design-based research methodology, two cycles of design, implementation, analysis, redesign, were used to obtain a set of principles to guide the design of an instruction-unit for high-molecular weight compounds. An important feature of the final unit was its use of dialogic teaching. Quantitative analysis showed a significant increase in students’ test scores in the redesigned instruction unit. To explain improvement, qualitative analysis showed the role of dialogical-based learning, the role of the teacher in prompting students’ understanding, and the nature of items chosen for the learning tasks. The importance of the work for chemistry teaching is that it shows the feasibility, at least, of introducing “Monomer”, “Macromolecule” and “Polymer” to younger students, previously thought unable to benefit from such more advanced concepts. Further research is necessary to improve and fine-tune the unit discussed.