a physical interpretative model of the phenomenon added to the poverty of the
formal models possessed by the majority of students. Few students in fact, less
than 10%, were able to mastery function as the sync square that is the product of two
elementary functions (RQ2).
These outcomes highlight that the representation are influenced by at least three
elements, not always harmonized and coherent: what a student has seen of the
pattern observed on the screen (a luminous spot of gradually decreasing intensity;
an alternation of maxima and minima); what is the student mental model of the
observed physical phenomenon; what are the mathematical/formal tools (analytical,
graphical) that the student is able to put in place (RQ2a).
The students of our sample activated at least five different models to account the
phenomenology. The first two remaster the geometric perspective (a spread of the
light as that of water flowing outside a pipe; reflection of light on the edge). A third
hybrid model attributes role for diffraction to the time part of a wave. Two other
models evoke elements of wave optics, without an effective modelling: the first
related diffraction to the waves hitting the slit edges; the second generically to the
constructive and destructive interference condition (RQ2b).
Regarding the basics of modelling, students demonstrated competence in knowing how to “measure” distances in wavelengths thanks to the tool used in the CLOE
lab and know how to set the condition for a maximum/minimum (71–78%). The
concept of order of interference and the condition producing it are clear only for a
minority of students. More than half of the samples (60%) identified the concepts of
superposition and sum of waves that is a spy of the problematic relation between a
concept and its formal representation (RQ3a).
The results discussed here indicate the activation of a process of revision of the
conceptions of the students based on geometric optics, but also highlight some
criticalities for instance related to overcome the phenomenological plane and to
build an effective wave model that we can presume can be faced by more active role
of students in lab (RQ3b).
The approach followed has shown to activate significant competences in the
students on the phenomenology of the optical diffraction and on the construction
of the wave model. Further work is required to make the students masters both
physical and math aspects involved. At the same time the formal aspects involved for
instance both in building of the phenomenological laws from the experimental
diffraction pattern and in the construction of the model, applying first principles
seems quite important to promote students’ acquisition of a functional understanding
of high level competencies both in math and in physics. Future researches will focus
on the interlacing of math and physics in the context of optical diffraction, in
particular concerning the phase of a wave and the role of time and spatial part for
interference.
Acknowledgement I thank for this work the discussion with Marisa Michelini and the PERG of
Uniud, and school, teachers and students participating in the research.
18 Student Learning Paths from Exploration of Optical Diffraction with Online. . .
235
formal models possessed by the majority of students. Few students in fact, less
than 10%, were able to mastery function as the sync square that is the product of two
elementary functions (RQ2).
These outcomes highlight that the representation are influenced by at least three
elements, not always harmonized and coherent: what a student has seen of the
pattern observed on the screen (a luminous spot of gradually decreasing intensity;
an alternation of maxima and minima); what is the student mental model of the
observed physical phenomenon; what are the mathematical/formal tools (analytical,
graphical) that the student is able to put in place (RQ2a).
The students of our sample activated at least five different models to account the
phenomenology. The first two remaster the geometric perspective (a spread of the
light as that of water flowing outside a pipe; reflection of light on the edge). A third
hybrid model attributes role for diffraction to the time part of a wave. Two other
models evoke elements of wave optics, without an effective modelling: the first
related diffraction to the waves hitting the slit edges; the second generically to the
constructive and destructive interference condition (RQ2b).
Regarding the basics of modelling, students demonstrated competence in knowing how to “measure” distances in wavelengths thanks to the tool used in the CLOE
lab and know how to set the condition for a maximum/minimum (71–78%). The
concept of order of interference and the condition producing it are clear only for a
minority of students. More than half of the samples (60%) identified the concepts of
superposition and sum of waves that is a spy of the problematic relation between a
concept and its formal representation (RQ3a).
The results discussed here indicate the activation of a process of revision of the
conceptions of the students based on geometric optics, but also highlight some
criticalities for instance related to overcome the phenomenological plane and to
build an effective wave model that we can presume can be faced by more active role
of students in lab (RQ3b).
The approach followed has shown to activate significant competences in the
students on the phenomenology of the optical diffraction and on the construction
of the wave model. Further work is required to make the students masters both
physical and math aspects involved. At the same time the formal aspects involved for
instance both in building of the phenomenological laws from the experimental
diffraction pattern and in the construction of the model, applying first principles
seems quite important to promote students’ acquisition of a functional understanding
of high level competencies both in math and in physics. Future researches will focus
on the interlacing of math and physics in the context of optical diffraction, in
particular concerning the phase of a wave and the role of time and spatial part for
interference.
Acknowledgement I thank for this work the discussion with Marisa Michelini and the PERG of
Uniud, and school, teachers and students participating in the research.
18 Student Learning Paths from Exploration of Optical Diffraction with Online. . .
235