The PERG of the University of Udine studied how to exploit the potentiality of
ICT to build effective educational proposals enabling students to acquire a coherent
vision of optical diffraction and a functional understanding of the wave model of
light (Corni et al. 1993; Santi et al. 1993; Michelini et al. 2004, 2014). The present
work regards a study on how high school students face light diffraction phenomenon
produced by a single slit, the model they activate exploring the phenomenology,
passing from geometrical optics, to a wave model of light. After a brief review on
researches on wave optics, the research instruments and context will be presented,
discussing then the students learning outcomes and concluding remarks.
18.2 Theoretical Background and Research Questions
Literature on how students face physical optics evidences a generalized and persistent tendency to use a geometrical model to interpret a diffraction phenomenon, or
hybrid models according to the different situations analysed (Wosilait et al. 1999;
Ambrose et al. 1999; Romdhane and Maurines 2007; Colin and Viennot 2000; Horn
et al. 2002). Students attribute a particle-like behaviour to a wave rather than the
behaviour of a perturbation propagating in space-time is evidently (Wittmann 2002;
Barnioli and Zavala 2016). Most students’ evidence difficulties in manage coherently wave model, for instance considering diffraction produced only by the edge
waves, often because of educational rituals: “. . .every slit is a point like wave
source. . .” (Ambrose et al. 1999). Many students do not have clear features of the
phenomena considered, confusing for instance refraction and diffraction, identifying
diffraction as an angular spread (Ambrose et al. 1999; Michelini et al. 2014;
Kryjevskaia et al. 2013).
In the specific of wave optics, some researches evidence that many students have
difficulties in applying the maxima/minima condition to solve also the simple
problem of interference (Ambrose et al. 1999; Romdhane and Maurines 2007).
This problem seems related to the difficulties of students to measure a distance in
terms of wavelength (Kryjevskaia et al. 2013). Other not well-studied conceptual
knots are the following: concepts of phase, optical path, wave front, optical ray in a
wave model; interpretative role of Huygens-Fresnel principle in explaining the wave
behaviour; distinction between amplitude and intensity of the light; constant uniform
light intensity observed/measured and oscillating nature of light perturbation.
To overcome these learning difficulties, different groups developed and tested
educational approaches based on research. The tutorials of the Washington University suggest an operative analysis of the interference starting from waves on a water
surface and simulating the interference of waves produced by two point sources
superposing the circles drawn on two transparent foils (McDermott et al. 2012). The
Maurines proposal builds the tools for optical interference studying different phenomenological contexts (Romdhane and Maurines 2007). Viennot stress the role of
the superposition principle and suggest analysing situations merging geometric and
waving optics image formation (Colin and Viennot 2000). Several proposals suggest
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A. Stefanel
ICT to build effective educational proposals enabling students to acquire a coherent
vision of optical diffraction and a functional understanding of the wave model of
light (Corni et al. 1993; Santi et al. 1993; Michelini et al. 2004, 2014). The present
work regards a study on how high school students face light diffraction phenomenon
produced by a single slit, the model they activate exploring the phenomenology,
passing from geometrical optics, to a wave model of light. After a brief review on
researches on wave optics, the research instruments and context will be presented,
discussing then the students learning outcomes and concluding remarks.
18.2 Theoretical Background and Research Questions
Literature on how students face physical optics evidences a generalized and persistent tendency to use a geometrical model to interpret a diffraction phenomenon, or
hybrid models according to the different situations analysed (Wosilait et al. 1999;
Ambrose et al. 1999; Romdhane and Maurines 2007; Colin and Viennot 2000; Horn
et al. 2002). Students attribute a particle-like behaviour to a wave rather than the
behaviour of a perturbation propagating in space-time is evidently (Wittmann 2002;
Barnioli and Zavala 2016). Most students’ evidence difficulties in manage coherently wave model, for instance considering diffraction produced only by the edge
waves, often because of educational rituals: “. . .every slit is a point like wave
source. . .” (Ambrose et al. 1999). Many students do not have clear features of the
phenomena considered, confusing for instance refraction and diffraction, identifying
diffraction as an angular spread (Ambrose et al. 1999; Michelini et al. 2014;
Kryjevskaia et al. 2013).
In the specific of wave optics, some researches evidence that many students have
difficulties in applying the maxima/minima condition to solve also the simple
problem of interference (Ambrose et al. 1999; Romdhane and Maurines 2007).
This problem seems related to the difficulties of students to measure a distance in
terms of wavelength (Kryjevskaia et al. 2013). Other not well-studied conceptual
knots are the following: concepts of phase, optical path, wave front, optical ray in a
wave model; interpretative role of Huygens-Fresnel principle in explaining the wave
behaviour; distinction between amplitude and intensity of the light; constant uniform
light intensity observed/measured and oscillating nature of light perturbation.
To overcome these learning difficulties, different groups developed and tested
educational approaches based on research. The tutorials of the Washington University suggest an operative analysis of the interference starting from waves on a water
surface and simulating the interference of waves produced by two point sources
superposing the circles drawn on two transparent foils (McDermott et al. 2012). The
Maurines proposal builds the tools for optical interference studying different phenomenological contexts (Romdhane and Maurines 2007). Viennot stress the role of
the superposition principle and suggest analysing situations merging geometric and
waving optics image formation (Colin and Viennot 2000). Several proposals suggest
224
A. Stefanel