June 22, 2008
June 22, 2008
June 25, 2008
13.191.1 - 13.191.11
An Intervention Using Concept Sketching for Addressing Dislocation-Related Misconceptions In Introductory Materials Science and Engineering Classes Abstract
In materials science and engineering (MSE) a major goal of the discipline is to effectively teach learners from other engineering disciplines about engineering a material's macroscale properties based on the knowledge and understanding of its atomic-scale structure. This goal is a significant intellectual challenge because learners must develop a conceptual framework to understand and solve materials-related problems in their own discipline. There are significant difficulties in addressing materials-related problems in a discipline because robust misconceptions are used by students attempting to understand and correlate the concrete "macroworld" of everyday objects, properties, and phenomena to the abstract "atomic and micro-scale world" of atoms, molecules and microstructure, which are types of features of a material that actually control its properties. These misconceptions, which are scientifically-inaccurate interpretations about materials, can neither explain nor predict materials' phenomena or properties. In this study, different teaching methods were used to address the question, "What is the effect of pedagogy on student conceptual understanding of deformation and thermal processing and associated property changes of metals in an introductory materials class?" For classes in 2002, 2003, and 2007, content delivered by lectures, pair-based discussions, and team-based concept sketching, respectively, were compared in teaching the effect of deformation or annealing on a metal's properties by invoking the atomic-level structural feature of dislocations to understand macroscopic-level property changes in strength, ductility, and fracture toughness. The effect of the pedagogy was assessed from responses to dislocation-related questions on the Materials Concept Inventory (MCI). Results showed that a team-based concept sketching pedagogy was most effective in achieving conceptual change of faulty mental models about deformation-related misconceptions. This indicates that concept sketching may be an effective pedagogy both for revealing misconceptions and achieving conceptual change about other physical phenomena in materials engineering, as well as diverse physical phenomena in other engineering disciplines.
Dislocations are a major structural feature of crystalline metals that play a significant role in their structure-processing-properties-performance relationships. The knowledge and understanding of the nature and behavior of dislocations is fundamental to understanding the relationships between features of a metal at the atomic and microscale level and at the macroscale level properties such as ductility, strength, and fracture energy. Since most incoming students in a materials class have little or no knowledge of dislocations, considerable time is spent teaching about dislocations and their role in processing and property change. In materials science and engineering (MSE) a major goal of the discipline is to effectively teach learners from other disciplines the relationship between a material's macroscale properties and its atomic-scale structure. But, this is a challenge because, in MSE, there is difficulty in learners constructing a useful conceptual framework which effectively links the concrete "macroworld" of everyday properties and phenomena to the abstract "atomic and microscale world" of atoms, molecules and microstructure, which are types of features of a material that actually control its properties.
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