Propagation of perturbations in elastic media: a modelling-based pedagogical approach

Università degli Studi di Udine, Italy

Supervisor: Prof. Marisa Michelini

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Abstract

This thesis focuses on the modelling of propagation of mechanical disturbances in elastic media from a pedagogical point of view with the goal of fostering particular forms of reasoning able to avoid the well-known learning difficulties in wave physics.

The treatment of the subject is carried out at two different levels. The former concerns the description of the proposed propagation model. The latter regards the design process and the experimentation of a teaching-learning sequence, based on the previous model, about the concept of mechanical wave propagation and the role played by media where waves are propagating.

The proposed model allows to obtain an easy definition of propagation speed in terms of the ratio between an information flux, which two elements exchange each other and the exchanged information. This kind of representation represents a different point of view with respect to the traditional one, based on the wave equation obtained by Newton second law, and offers a conceptual explanation
of conditions making the propagation speed an intrinsic property of the medium. Such behaviour may be observed only under the particular condition of proportionality between information flux and information itself. It is shown that this condition leads to the non-dispersive regime for wave propagation and that the canonical wave equation for continuous media descends from model equations.

The framework used in designing the teaching/learning sequence is the model of “Educational Reconstruction”. According to this model, the designing of an effective teaching/learning environment involves a deep analysis of empirical studies about students’ views of the physical field in order to point out the learning opportunities as well as the difficulties to be expected. Secondly, the content structure has to be analysed from the scientific point of view as well as from the perspective of the educational aims.

The T/L sequence is divided into steps each composed by various micro-activities. It focuses on local mechanisms regulating the propagation of information through a system composed by interacting elements as well as on its quantitative description. The approach is based on modelling strategies by using simulation environments and laboratory activities.

In the thesis are also reported the results of a teaching/learning experiment, involving a sample of 75 high school students. Data analysis is mainly based on qualitative research methods. The main focus is on students’ representations of phenomena and on the cognitive strategies put in action in order to modify or support their descriptive and interpretative mental models. Results are discussed by pointing out the efficacy of strategies focusing on the process of constructing predictive conceptual models and by identifying the concept of ‘level of analysis’ as different ways to look at the same phenomenon.

Reference List
C. FAZIO, I. GUASTELLA, R.M. SPERANDEO-MINEO AND G. TARANTINO “Modelling mechanical wave propagation: guidelines and experimentation of a teaching learning sequence” International Journal of Science Education, vol. 30 (11), 1491-1530 (2008)

G. TARANTINO “Un approccio alle onde meccaniche attraverso un modello di propagazione” Giornale di Fisica, vol. 49 (3), 145-159 (2008)

G. TARANTINO “Elastic waves: mental models and teaching/learning sequences” Frontiers of Fundamental Physics, B. G. Sidharth, F. Honsell, A. de Angelis eds., Springer, 2006, the Netherlands, p.385

G. TARANTINO, C. FAZIO AND I. GUASTELLA: “Designing and validating a teaching/learning sequence about elastic waves propagation: the role of pedagogical tools ”. Proceedings of ESERA 2005 Conference “Contribution of Research to Enhancing Students’ Interest in Learning Science”, Barcelona, Spain, 28/8 – 1/9 2005 (vol. V, pp. 633-636)

Corespondence
Giovanni Tarantino

Unità di Ricerca in Didattica della Fisica (URDF),

Gruppo di Ricerca per l’Insegnamento e Apprendimento della Fisica (GRIAF)
Dipartimento di Fisica e Tecnologie Relative, Università di Palermo Viale delle Scienze Ed. 18, 90100, Palermo, Italy
e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it. 

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