Teaching stress-strain behaviour of ductile and brittle materials using concept-context maps to mechanical engineering freshmen

Stress-Strain relations are graphical measures to determine the mechanical properties and morphology of engineering materials. In engineering universities, stress-strain curves are introduced in the introductory course of materials science for the mechanical, metallurgical and civil engineers. Stress-strain diagrams can be easily plotted from experimental data obtained from the uniaxial tensile testing of specimens made as per standards of engineering material. However, understanding of the metal's deformation, dislocation behaviour, as well as the microstructure, is considered challenging. Common teaching aids present stress-strain diagrams as a working tool but does not explain how to relate various attributes like microstructural characteristics and mechanical behaviour with its engineering properties. This accumulated difficulty leads to a decreased level of motivation among first-year engineering students. The article presents CC maps an instructional strategy to gain sustainable knowledge on how to read stress-strain characteristics, interpret engineering properties and promote cognitive transfer in learning. The results obtained indicated that intervention of CC maps has improved conceptual understanding, learning interest and performance of students in the class.