CURRICULAR PATHS IN THE SUPERCOMET 2 EXPERIMENTATION IN ITALY

CURRICULAR PATHS IN THE SUPERCOMET EXPERIMENTATION IN ITALY Federico Corni, Marisa Michelini, Lorenzo Santi, Alberto Stefanel, Rossana Viola ABSTRACT Supercomet (SUPERCOnductivity Multimedia Educational Tool Phase 2) is a project within the Program Leonardo da Vinci Phase II of the European Union, involving Universities and Secondary Schools of 15 European countries The objectives of this project are the production of a multimedia tool for teaching superconductivity and the creation of an international community at European level, able to revitalize the teaching of physics in order to open new international collaborations Several materials have been developed in this framework: interactive animations; texts; videos; hands-on materials for demonstrating and measuring phenomena related to superconductivity and electromagnetism, with an accompanying teacher guide and a teacher seminar These materials have been used both in teacher seminars and training and in the classroom experimentation in the partner schools In Italy the University of Udine led and coordinated the experimentation that involved students from several schools within several Italian regions The planning of the paths by the teachers involved in the project points out various curricular proposals concerning approaches, methods and contents The analysis of these paths gives a wealth of statements concerning two main ways to look at superconductivity: electric properties and magnetic properties A report of the main results of the analysis of these paths will be presented KEYWORDS Superconductivity, Curricular innovation, design and experimentation of curricular path; practitioner research INTRODUCTION Topics of modern physics in the curricula of secondary school, and in particular, applications of quantum physics, offer meaningful occasions of formal thinking development, showing how modern physics develops knowledge in the atomic world (Pospiech, 1999; Zollman 2000) Classical physics is regarded as a modern working tool, useful even for scientific exploration of themes developed in the 20th century (Corni et al 1996) Superconductivity in this sense gives also the chance of explaining and exploring technological applications that currently have a remarkable social impact, such the NMR, the Maglev, the supermagnets, or that will likely have in the near future, such the applications in superconducting electronic elements The European projects Supercomet (SUPERCOnductivity Multimedia Educational Tool Phase 2) and MOSEM (Minds-On experimental equipment kits in Superconductivity and ElectroMagnetism for the continuing vocational training of upper secondary school physics teachers) are aimed of involving universities and secondary schools of 15 European Countries (Engstrom et al 2008) The main materials produced during the first phase of the Supercomet project (SC2 in the following) were various: interactive animations, text, videos, hands-on materials for demonstrating and measuring phenomena related to superconductivity, electromagnetism and electrodynamics (Engstrom 2004) These materials (CD-SC in the following) have been used both in teacher seminars and training, and in the classroom experimentation in the various partner schools In Italy the University of Udine led and coordinated one of the wider pilot experimentations within the cited projects, involving students and teachers from several schools from Sicily to Bolzano and Udine in the northern Italian regions The materials and the general features of the experimentations have been discussed elsewhere (Michelini, Viola 2008 a,b; Michelini et al 2008 a,b) Such features will be synthesized here, focusing on the content choices and on the paths followed In a perspective of practitioner research, four of the experimented didactical paths (Rudduck 1989; Elliot, Sarland 1995; Bransford, et al 1999; Taber 2000; Dutto, Michelini, Schiavi 2004), will be presented They allow the various approaches to be outlined Finally, the emerging suggestions for a curricular design about superconductivity will be proposed and discussed RESEARCH QUESTIONS This contribution, that report from the SC2 experimentation in Italy, intends to answer the following research questions: RQ1) feasibility of superconductivity paths in secondary school RQ2) typologies of teacher choices as concerns the disciplinary, methodological plans, as well as of the strategies and of the working styles; way how superconductivity is integrated into the actual cussicula RQ3) topics mainly considered relevant by the experimenter teachers RQ4) assessment of the SC2-CD tool and way of integration with the experiments SAMPLE AND MONITORING TOOLS OF SC2 EXPERIMENTATION Table reports a list of the Italian schools coordinated by the University of Udine that participated in the SC2 project during the two years of materials development The rich picture that emerges constitutes a value added to the experimentation, since it documents very different experiences in geographic context, school level and student age, developed with different working styles, disciplinary approaches, and didactical choices In spite of this diversity it was possible to analyze the various projects according to the following common elements: the experimenter teachers attended the same training (Michelini et al 2008 b); the CD-SC proposals were included in all the didactical paths; the documentation of the experimentations was based on a portfolio composed by six monitoring worksheets, prepared following the results of a previous research aimed to individualize tools for the evaluation of didactic innovation (Aiello Nicosia et al 1997) The portfolio worksheets are studied to collect defined and homogeneous information about each class involved in the experimentations regarding physics teaching/learning and in particular as concern to:  Class presentation (previously experimentation carried out, physics contents familiar to the students, laboratory and computer use, usual methods of teaching, average attitude of the class)  Departure point for each student (ability, interests, attention, socializing, school performance)  Board diary of various activities carried out (daily notes: data; activities; time extension; contents; experiments in lab; section of SC-CD used; homework assigned; problems emerged; qualitative evaluation of student feedback and teacher satisfaction about work made)  Final report (text in free form containing evaluation of materials, difficulties met with modules contained on the SC-CD, reactions of the students, evaluation of the experiment, suggestions)  Final students evaluation (attention, active involvement, school performance in experimentation)  Student interview according with a grid (one interview per student group performance) 2006/07 Web Drago Partner Schools Testing Schools 2005/06 Table Schools participating in the SC2 experimentations *: classes of the sample a.s Type Institute City Classes (age) Liceo Scientifico “M Grigoletti” Pordenone 2* (17-18) ISIS “R D’Aronco” Udine Liceo Scientifico “G Marinelli” Udine 2* (15-16) Liceo Scient.Tecnologico “Malignani” Udine 1* (17-18) Ist Istr Sup “Q Cataudella” IST “Carducci” (classic section) Liceo Scientifico “Berto Students 19 51 22 Scicli (Ragusa) Vibo Valentia Comiso (Ragusa) 1* 1* 1* 11 Liceo Scientifico “E Torricelli” ITI “E Fermi” Liceo Scientifico Statale Tricarico ITI A Malignani ISIS R D’Aronco Bolzano Modena Tricarico (MT) Udine Gemona (UD) 3*-1 (17-18) 1* (15-16) 1*-2 (17-18) 1* (17-18) 1*-1 (14-16) 36 27 63 21 25 IPSIA “Galilei” Bolzano 1*-1 (14-16) Partner Schools ITIS “A Volta” Palermo 3* (17-18) 53 The monitoring tools are mostly aimed to follow the process of experimentation carrying out, instead of the student learning The only systematic data, though indirect, about learning are the evaluations which the teachers, in free ways, have expressed about the learning of their students at the end of the experimentations Significant elements, even if not systematic, can be collected also from the board diaries and from the interviews The total number of students involved in the experimentations was 348, with a total of 110 students between the ages of 14-16 and 238 between the ages of 17-18 The students were from 22 classes in 12 schools in 10 different seats distributed in all Italy In this paper we will consider only the 17 experimentations, indicated in Table with an asterisk, that produced a complete portfolio of the monitoring tools ANALYSIS METHODS OF THE EXPERIMENTATION PROJECTS The portfolios were analyzed according to the following criteria: 1) Experimentation typology; 2) Curricular approach to superconductivity and contents; 3) methodology and performed experiments; 4) Teaching style and strategy We will discuss extensively the analysis of points and 3, and synthesize the other points, as they were object of previous works (Michelini, Viola 2008 a,b; Michelini et al 2008 a,b) 1- Experimentation typology The ways in which the experimentations have been planned, prepared, executed and monitored were conducted by three main perspectives: 1) the SC2 material validation; 2) the didactical innovation also by means of information and communication technologies; 3) the research about the teaching/learning processes - Curricular approach and disciplinary contents A first level of global analysis is based on the whole experimented path to identify the guidelines, the elements of feasibility, information about the learning and the difficulties of the students, and suggestions about the integration of traditional curricula and innovative proposals A second level of analysis concerns the macro-subjects, examining which experimentations considered the various phenomenological as well as conceptual aspects In such way it is possible to distinguish who pointed to the phenomenological analysis and who pointed to the use of models in the discussion of the considered phenomena; who kept the treatment at a qualitative level and who integrated the SC2 materials on a formal plane 3- Methodology The following activities were prevailing in the class activities: teacher conducted demonstration laboratory and/or student conducted laboratory; simulations; integration of laboratory and simulation 4- Teaching style The main teaching style characterizing the experimentations are: group activity, dialogued lesson, student presentation RESULTS OF THE EXPERIMENTATION GLOBAL ANALYSIS In Table the results of the analysis of the SC experimentation sample according to the four selected plans are summarized All experimentations have been classified into one of the categories attributed to each plane, obtaining a multidimensional classification The SC experimentations were performed with the following typologies:  TS-A) research experimentation, with preparation of paths and didactical materials, within: TS-A1) Scuola di Specializzazione per l’Insegnamento Secondario - Specialization School for Secondary School Teaching - (SSIS), by teachers in first formation; TS-A2) didactical experimentations conducted by in service researcher-teachers  TS-B) Activity of research-action in a blended mode, from the Drago network schools, where were also considered presentations prepared and managed by the students (Michelini, Gianino 2007) One experimentation conducted in presence had analogous characters  TS-C) Experimentations for the validation of the SC2 materials, during regular didactical activities by teachers who attended the formation course provided by the project The largest group of experimentations is TS-C, due to the main objective of SC2 materials validation For this reason it is particularly meaningful that more than half of the sample (9 of 17) conducted works with clear research character (TS-A, TSB) The second section of Table (AC) shows that in the SC2 experimentations, both in the first two years and in the last three years classes, the approach AC-1 was frequently followed, which introduces the superconductivity through the magnetic properties of materials Such choice is motivated by the more simplicity in the observation of the Meissner effect compared to the measurement of the resistivity  versus temperature T, as provided in AC-2, used in different schools The other two approaches, AC-3 and AC-4, are meaningful due to their innovativeness, even if used in only one school Most of the experimentations (60-10% of the sample) were based on an experimental methodology, often integrated with the CD-SP, and a style of teaching, which assigns an active role to students: these are the elements that qualify the Italian SC2 trials (sections ME and SL of Table 2) TREATED CONTETS In this section, the disciplinary contents, considered in SC2 experimentations, will be discussed, divided into six main macro subjects (electrical conduction; magnetic phenomena, generated by magnets and by electrical currents; electromagnetic induction; superconductivity) Table Analysis of the experimentations by: typology; curricular approach; working style N: number of experimentations; %: percentage over the whole experimentations (N=17) TS - Typology N % TS - A1 Research experimentation SSIS apprenticeship 18 TS - A2 Research experimentation of in-service teachers 18 TS - B Research action – web laboratory/student presentations 18 TS - C SC material validation 46 AC – Curricular approach N % AC-1 Ordinary magnetic phenomena, introductory to magnetic properties of 11 65 superconductors AC-2 From electric conduction to conduction properties of superconductors 18 AC-3 Energy transformations to understand superconductivity 12 AC-4 Approach to superconductivity through its technological applications ME – Didactic methodology N % ME-1 Experimental laboratory (qualitative and quantitative experiments) 29 ME-2 CD-SC2 multimedia materials 29 ME-3 Integration of CD-SC and of experimental activities 35 ME-4 Experimental analysis, motivated by the study of technological applications SL: Teaching style N % SL1 – experimental approach conducted by the students 47 SL2 – presentations by the students 24 SL3 – lectures and/or dialogue lessons, also with experiments 29 Electric conduction In Table the more frequently explored aspects in the CS2 experimentations about electric conduction are summarized Most teachers was led to introduce or recall phenomena and concepts related to electricity, often with experimental approaches In general, ohmic elements have been considered, and only in one school non ohmic circuit elements have been analyzed Table Electric conduction: aspects explored in the majority of the experimentations; SC: aspect present in CD-SC; n: number of experimentations and (%) percentage over the whole experimentation SC2 (N=17) Aspects explored in the majority of the experimentations SC N % Conduction in general and descriptive quantities SC 11 65 I-V characteristics of ohmic circuit elements (Ohm law) SC 12 71 Resistivity – relation with T SC 10-9 59-53 Drude model for conduction SC 47 Three subsets can be recognized: A) the first one only explored the relation between resistivity  and temperature T (4/12 experimenters); B) the second subset qualitatively introduced the microscopic Drude model, without obtaining the consequent relation between  and T (3/12); C) the third one considered both aspects (5/12) The various choices reflect the adopted approaches: purely phenomenological (A); more oriented to the construction of an interpretative model (B); integration of the first two (C) Magnetic phenomena: interaction between magnets and between magnets and ferromagnetic objects The aspects related to magnetic phenomena produced by permanent magnets are summarized in Table With the exception of two cases of clear choices of methods and contents, all teachers who developed this topic considered also the analysis of electric conduction Two subsets can be recognized, almost separated: A) the first one, composed by teachers, that preferred to operate with phenomenological exploration, in various ways, with: the compass, iron filings, magnetic needle arrays, to evidence the magnetic field as generalization; B) the second subset, more orientated to the construction of interpretative models, composed by teachers who considered the Weiss model Table Magnetic phenomena produced by magnets SC: aspect present in CD-SC; pi: integrative proposal; PI: innovative proposal; n: number of experimentations; %: percentage over the whole SC2 experimentations (N=17) Explorated aspects SC pi PI n % Permanent magnets SC 10 65 Interaction between magnets PI 10 59 Phenomenal Relation between magnet interaction forces and distance PI 41 aspects Magnetic properties of materials SC 53 Compass near a magnet SC 10 59 Iron filings/rods near a magnet pi 41 Field lines for magnetic field representation SC 10 59 concepts Magnetization SC 53 Weiss domains SC 29 Magnetic phenomena produced by and on currents The section of the magnetic phenomena produced by and on electric currents, summarized in Table 5, have been considered by more than half of the experimentations, most frequently with phenomenological explorations The slant given to discussion about these themes in CD-SC was presumably in harmony with the choices traditionally performer by teachers It is important to observe that the descriptive-qualitative slant that characterized SC-CD was, in particular for this theme, also the slant prevalently employed by experimenters, proven by the low frequencies in the last section of Table Table Magnetic phenomena produced from and on currents SC: present in CD-SC; pi: integrative proposal; n: number of experimentations; %: percentage over the whole SC2 experimentations (N=17) Explored/considered aspects SC pi n % Oersted experiment SC 53 B generated by current across wires (exploration with a compass) SC 10 59 Concepts Phenomenology B generated by a coil/solenoid Ampere experiment Interaction between coil/solenoids Pohl experiment SC 10 59 SC 53 SC pi 35 SC Biot-Savart law Expression of the magnetic field generated by a coil Expression of the magnetic field generated by a solenoid Magnetic force on a wire crossed by current: F= i dl  B pi pi pi pi 53 18 29 Electromagnetic induction Analyzing the last columns of Table 6, it follows that the aspects of electromagnetic induction have been treated by more than the half of the sample of experimenters (13 experimenters, 78%) All the experimenters, with the exception of one, are those who followed the AC1 approach and the two ones who followed the AC3 approach The explorative part was completed by almost all the experimenters with the concept of flux of B (11/13) and the law of Faraday-Neuman-Lenz (9/13), as suggested by SCCD Nevertheless, only two schools considered the role of the flux in the electromagnetic induction, in spite of that of the relative motion Conc Phenomenology Table Electromagnetic induction SC: present in SC-CD; PI: innovative proposal; experimentations; %: percentage over the whole SC2 experimentations (N=17) Considered aspects SC PI Relative motion of coil and inducting system (magnet or coil) SC Current variation in a solenoid into another solenoid SC Insertion of a coil into a magnetic field B (Faraday exp.) SC P.D induced by a straight wire moving into a magnetic field PI Emf induced between coupled solenoids with air gap and transformer SC Induced voltage generators (alternator, dynamo) SC Magnet that falls through a coil PI Motion of a magnet through a metallic pipe and induced emf SC Flux of B and its variation SC Faraday-Neumann-Lenz law SC n: number of N 10 10 13 11 % 59 59 24 41 47 12 77 65 53 Experiments about the effects of low temperatures over electric resistivity The two proposed experiments in SC-CD are those of the Thomson wire, explored in 10 experimentations (59% of the sample), and of the LED diode that turns off when immersed into liquid nitrogen, proposed in experimentations (29%) They have been selected because they are meaningful in order to join electromagnetism phenomenology and low temperature phenomenology, superconductivity in particular Superconductivity The aspect considered in each case was the existence of the critical temperature T c (Table 7) Table Superconductivity; SC: present in CD-SC; PI: innovative proposal; experimentations; % percentage over the whole SC2 experimentations (N=17) Considered aspects SC Events that led to the discovery of superconductivity Resistance as a function of T for a superconductor Levitation of a magnet over a superconductor Stability of magnetic levitation Type I and II superconductors n: number of SC SC SC PI SC % (N=17) 11 65 15 88 16 94 53 PI n ConceptsPhenomenolog Technological applications Suspension of a magnet under a superconductor SC 24 Phase transition temperature Meissner effect Critical current and critical field Anomalous behaviour during phase transitions of the relevant quantities Formation and behaviour of Cooper pairs BCS theory for I type superconductors Penetration depth Vortex in II type superconductors and pinning Circuits with superconductive elements Josephson junction Widenes of superconductivity applications Maglev MNR Superconductor bearing Transport and storage of electric energy Superconducting components in microelectronics Superconducting sensors Supercomputer (computer with superconducting elements) SC SC SC SC SC SC SC SC SC SC SC SC SC 17 15 11 11 6 100 88 41 65 65 41 29 24 12 35 24 29 35 24 29 12 PI PI PI PI PI PI PI The phenomenon of magnetic levitation and the behaviour of the resistivity near the critical temperature, discussed with simulations and only in two cases experimentally, were largely explored (94% and 88% respectively) The qualitative slant given in general to the treatment of superconductivity emerges from the fact that the experimenters who considered the knots of the presence of critical currents and magnetic fields, the vortex in II species superconductors (4 cases) and pinning (3) are the minority part of the sample The analysis of circuits with superconducting elements was inserted organically only in two cases STUDENTS LEARNING The teacher evaluations about the student learning are summarized in Figure for the students aged 1416 and 17-18 They are asymmetrical distributions with positive and very positive averages It follows that the teachers evaluated sufficient 80% learning, i.e that most of the students overcame the principal knots of the various paths The main difference between the two distributions is in the position of the maxima: very positive (4) for the younger students, positive (3) for the others This difference is due presumably to the fact that the younger student approaches have a more qualitative and descriptive character than those of the 17-18 aged students, particularly for what concerns the part devoted to superconductivity In addition, it can be also considered the great enthusiasm of the young students about the surprising aspects of physics These data, though indirect, indicate that the proposals designed by the experimenter teachers are suitable for secondary school and Figure Distributions of the teacher evaluations of their produce positive attitudes in the students for the two age groups (1- definitely negative, 2mediocre; 3- positive; – very positive) students, either about participation, or about learning They confirm the importance of inserting elements of modern physics into the curricula, integrating them, in particolar, with aspects more traditionally treated in physics education For what concerns the teacher suggestions about the main difficulties encountered by students, the only critical point concerns the knot of the process of Copper pairs formation In the experimentations where this knot has been considered (more than 50%), all students initially encountered difficulties, subsequently overcome by only part of them (50-60%) Analogous difficulty emerged during the training workshops for teachers In about 1/3 of the experimentations some aspect of technological applications have been considered (Table 7), often in a discursive/descriptive way CURRICULAR INDICATIONS FROM THE ANALYSIS OF THE TREATED ARGUMENTS The choice of the experimental exploration of the Ohm law or of the magnetic phenomena to approach superconductivity allows the investigation of aspects of classical physics which comprehension supplies important bases for the exploration and the understanding of modern physics; the analysis of the classical interpretative limits opens as much as discussion thread about quantum phenomena In this perspective, the process of modelling and of construction of formal thinking have an important role The more qualifying choice of the experimenting teachers was the combining of experimental activities and simulations The qualitative character of the SC-CD simulations to develop the adaptability to different contexts does not have to orientate to a uniquely descriptive approach, as that observed of the magnetic field produced by currents, or for electromagnetic induction (Galili and Kaplan 1997; Maloney et al 2001; Stefanel 2008) For the interpretation of conduction phenomena, especially in order to introduce superconductivity, the models play an important role The challenge is to construct a quantum interpretation, rather than to introduce classical models as the Drude model, effective on a qualitative plane, but notoriously inadequate for the description of the simple relation between  and T The genuinely quantum nature of the processes involved does not emerge even with semi classical models (Milkman, Halkias 1967; Kittel 1966), which clarify single phenomenal aspects, but favour the loss of a coherent picture, often causing learning difficulties (Steinberg et al.1999) A non reductionist approach to phenomena of conduction and superconduction must be founded on descriptive and interpretative quantum categories Similar considerations are about the Weiss model, that is based on the assumption of the existence of an average magnetic field, which intensity is not compatible with that of a field produced by parallel atomic dipoles An understanding, even elementary, of ferromagnetism is given only recognizing the electrostatic nature of the energy associated with magnetization (Van Vleck 1978) The problem is not of secondary importance due to the intrinsic interconnection between the superconducting and magnetic properties The challenge, obviously, in not the introduction of a difficult formalism into school, even with university competences, but the elaboration of proposals formally accessible to secondary school students, coherent with the quantum description of phenomenology These considerations are supported by the difficulties encountered by students and teachers to understand the model for the formation of Cooper pairs in SC2 Such a model, reported in many textbooks of structure of matter as well as popular texts (http://en.wikipedia.org/wiki/Cooper_pair), refers to the (local) deformation of the lattice while an electron passes This deformation, determining a local excess of positive charge density, leads to the attraction of another electron In this way the two electrons form the Cooper pair Such a mechanistic explanation is not able to answer various questions (why Cooper pairs are formed in the superconducting state and not in the ordinary conductor state? Why the process occurs below a certain temperature? Why a pair is stable? Why this mechanism is effective only for some conductors?) Its main weak point is that it refers to the Newtonian paradigm of force, while the process, being essentially quantic, requires an analysis from an energetic point of view The treatment of the technological applications of superconductivity correspond to a particular need of students, as emerged from an exploration with students both from Lyceum, and from Technical Institutes (Disint et al 2008) An approach, as illustrated in the following, that integrates the exploration with the understanding of the concepts, brings the didactical potentialities out THE PATHS OF THE EXPERIMENTATIONS PERFORMED In this work, the various approach choices of the performed experimentations will be summarized into four paths “Introduction to superconductivity” - approach through the magnetic properties The research experimentation has been realized in apprenticeship activity (TS-A1) from a prospective teacher (M Braida) during the 2005/06 school year in a terminal class of technical Lyceum – age 17-18 of the ITI Malignani of Udine, with the collaboration of the class teacher and the supervision of one of us (MM), following an approach to the magnetic properties os superconductors (AC-1), with active role of the students (ME-1) and activity performed in groups (SL1) The experimentation took in total 10 hours, two hours for the pre-test and the post-test and hours of experimental and simulation activities Integrating and qualifying part of the project are the didactical instruments prepared and used in the experimentation:  Eight working forms, one per lesson of the path, projected to stimulate a problematic attitude and collect elements about the learning processes  One test about the main knots of the path, employed as pre-test and post-test  One synthesis document about the superconductivity to support individual study of the students The thread of the contents will be presented with its segments (M1-M8), indicating in parenthesis the progressive number of the experiments effectively done by the students M1 – The interaction of a magnet with various objects made of different materials is explored (Esp 1a) The behavior classes are individuated by: 1) iron, or steel, or nickel (ferromagnetic), 2) non metals and many metallic objects (copper, bronze, aluminium) It is recognized that not all metals exhibit ferromagnetic properties The exploration of the interaction is completed with the recognition of the reciprocity and of the dependence on distance The ability of the magnet of modifying the space properties introduces the magnetic field, which is represented by means of field lines constructed using little compasses, iron filings, single compasses (Esp 1b) Such representation gains formal meaning when it is observed that the different superficial density of lines can be correlated to the field intensity M2 – The interaction between two magnets is explored (Esp 2): ring-shaped magnets are piled, by means of a wood bar, and bar-shaped magnets are faced, being free to rotate By progressive degrees of exploration, the following steps are followed: recognition of the bipolar nature of the magnetic field sources, construction of the relation force-distance between poles of magnetic rods in one direction (Esp3a) and role of the pair of forces in the interaction (Esp 3b) M3 – While rod magnets (or button shaped) in a vertical (or inclined) plastic pipe (or on a guide) fall with accelerated motion, when they are put into a copper pipe (or guide) very slowly The recognition of the role played by the emf and then of the induced currents in the copper pipe-guide leads to the interpretation of the phenomenon The field produced by these induced currents, in this case has the opposite verse of the inducing field and then is responsible for the evident slowing down of the falling magnet The experiment, first executed with an integer pipe (Esp 4a), then with a pipe with longitudinal cuts (Esp 4b), can effectively conduce to a quantitative analysis with traditional apparatus M4 – The phenomena of electromagnetic induction and of magnetic suspension are reconsidered by studying the experiment of the Thompson ring, proposed to show the influence of T on  (Esp 5) The experiment, repeated with rings of different materials allow to recognize that there i san analogous behaviour due to the strong field produced by the induced currents, which are as intense as low is the ring temperature The evident decrease of resistivity is associated to the decrease of temperature of the material of the ring M5 – By analogy with the Thomson ring, the behaviour of a magnet on a frozen superconductor is explored (Esp 6) The levitation of the magnets is compared with the analogous situations observed before: the experiment of the floating magnets suggests that the magnet must be subjected to an opposite field; the experiment of the falling magnet into the copper pipe indicates that the effect tends to auto regulation, i.e it is produced by an induced field; the fact that the magnet levitates but does not fall, as the case of the magnet into the copper pipe, indicates that the induced field must be equal to the inducing field, or that the superconductor behaves as a perfect diamagnet (Meissner effect) The effect of induction produced by the presence of the magnet does not stop when the magnet is still, (as happens with an ordinary conductor) then in the superconductor the dissipative effects must be absent, or 0 M6 – The experimental exploration of the Meissner effect introduces to the view of the main events leading to the discovery of superconductivity, characterizing the type I and II superconductors phenomenology, describing the anomalous behaviour of the three quantities which exhibit critical values in superconductors: magnetic field, current and temperature M7 – A short view of the technological applications of superconductors offers the opportunity of interdisciplinary connections of various types, given the relevance of the use of superconductors in the electronics and sensors fields (cryoelectronics and superconductor sensors), medical diagnostic (NMR), and in the advanced physics researches (superconductor magnets) M8 – The explorations in segments and suggest the discussion the basic elements of the BCS theory, the only one that accounts for I type superconductors About this theory, can be discussed the role played by the lattice in the production of neat attractive effects between electrons, i.e in the formation of the Cooper pairs, and the effect of condensation of such pairs, not subjected to the exclusion principle Approach to superconductivity through the exploration of the resistivity This path has been proposed and experimented by W Manzon, in service teacher in the fifth year class (age 18-19 ) of the Liceo Scientifico Statale “M Grigoletti” in Pordenone It is an example of validation of SC2 materials (TS-A3), following an approach to the electrical conduction properties of superconductors (AC-2), which integrates the use of SC-CD with experimental activities (ME-3), using dialogued lessons and demonstration experiments (SL3) It develops in the steps (R1-R5) discussed in the following, in parenthesis the experiments proposed and realized with students are reported in parentheses R1) Experimental exploration of the I-V relation for ohmic elements, (Esp 1a): Ohm’s law and prevision of the behaviour of currents measured in simple resistive circuits (Esp 1b) From resistance to resistivity  as electric property of materials and generalized Ohm law (Esp 1c) R2) The experimental study of  vs T (Esp 2) offers the opportunity of discussing the microscopic model of the Fermi gas to describe the conduction in metals at room temperature R3) The problem of studying the behaviour of (T) near K has been posed The residual resistivity r = const due to defects and impurities of metals disappears in superconductors The focus on the critical transition, reached in the laboratory for a type II superconductor immersed into liquid nitrogen, allows the sharp phase transition of the superconductor, responsible of the resistivity fall, to be reconstructed R4) The sharp change of conduction properties in a small temperature interval evidences the nature of phase transition of the process An interpretative model for such transition is then searched, and the BCS model for I type superconductors is discussed R5) A simulation allows the electric circuits explored in step R1) to be reanalyzed, substituting an ordinary resistive element with a superconductor (virtual) (Esp 4.) It leads a) to reproduce the experimental conditions, assigning the values of the resistors employed in the laboratory; b) to examine, point by point, the resistivity vs temperature, down to the sharp fall at T=Tc, for the recognition of the qualitative and quantitative change in circuit behavior; c) to analyze the redistributions of the voltage falls at the extremes of the various circuit elements, recognizing the role and the function of the superconducting elements The energy transformations and superconductivity The path is planned by the in-service teacher V Capocchiani and experimented by herself and R Sangoi in two second year classes (15-16 age) of the Liceo Scientifico “Marinelli” in Udine for a total of 32 hours, more than the half dedicated to experimental activities It is different from the previous approaches since employs the energy transformations AC as basis for a mostly experimental approach (ME-1), integrated with the SC-CD modules and with active role of the students (SL-1) It fits organically to the argument of mechanical energy transformations, typically considered in second year curricula The detailed path of the steps is the following (E1-E5) E1) In the context of mechanical energy transformation into different forms, the electric transformations in particular are analyzed It is recognized that there are different ways, static and dynamical, to produce 10 electric energy (Esp 1) The electrostatic and magnetostatic fields are explored and compared (Esp 2) The experimental exploration of DC circuit, with traditional instruments and on-line sensors (Esp 3a), is integrated with the discussion of the SC-CD th module The phenomenology is described through the first and the second Ohm laws and their limits are discussed considering the I-V characteristic of a bicycle lamp (esp 3b), discussing the energetic processes (Joule effect – Esp 4) E2) The electric current magnetic effects are introduced with qualitative experiments (Esp.5 and 6) and the module of SC-CD, integrated with an activity of formalization The magnetic fields generated by magnets are visualized by constructing the field lines with iron filings and compasses The Oersted experiment (Esp 7) is completed with the Biot-Savart law for a straight wire The magnetic fields produced by currents are deepened in terms of formalization and description with the experimental and simulated exploration of the Ampère and the Pohl experiments (Esp e 9) E3) The description of the magnetic effects of currents is completed analyzing the filed produced by coils and magnets at first experimentally explored in laboratory (Esp 10 e 11), then considered using the module simulations of SC-CD E4) The students, in groups, explore the way to produce induced emf (Esp 12) The concept of flux is introduced and clarified The transformer (Esp 13) and the dynamo alternators (Esp 14) working behaviours are analyzed as occasion to reinforce the concepts of induction and alternate currents The energetic processes involved in the transformers are analyzed E5) In groups, the students explore the interaction between piled magnets (Esp 15) and various situations of levitation of a magnet on a superconductor (Esp 16) With the same strategy previously adopted, in this module too the experimental exploration and the superconductivity interpretation are integrated, discussing in particular the formation of the Cooper pairs A short discussion about the application of superconductivity completes the path Approach to superconductivity starting from the exploration of its applications The path has been projected by the apprentice teacher M Gnech, of the SSIS in Bolzano and experimented with students of the fifth year of scientific lyceum (18-19 age), with the supervision of one of us (FC) (TS-1), following an approach based on the discussion of the technological applications of superconductivity (AC-4), using a working method that gives an active role to students in the laboratory, integrated with the use of videos and simulations, dialogued lessons (ME-3), with alternated phases conducted by students (SL1) and with frontal activities (SL-3) In the following the thread of the didactical path A preliminary phase recalls the main knowledge about electric conduction Simple circuits with linear elements are taken into consideration to reconstruct the Ohm law (Esp 0a) The relation between resistivity and temperature is experimentally explored and recognized (Esp.0b) The theme of superconductivity is introduced with the videos about Maglev, MNR, magnetic bearings, supercomputers Such videos motivate the explanatory investigation The experiment about the magnetic levitation (Esp.1a), allows the behaviour of a perfect diamagnet to be recognized in a superconductor: the Meissner effect, that is used for an experimental exploration about the behaviour of a superconductor with temperature Tc is recognized and measured (Esp.1b) The extraordinary behaviour of a superconductor for temperatures lower than Tc leads to explore also the properties of a superconductor and in particular those of electric conduction The main elements characterizing the superconducting phenomenology are discussed: the existence of a critical temperature Tc, of a critical field and of a critical current; the penetration coefficient A simple electric circuit employing a superconductor switch is the context that is proposed for the recognition of the fact that also the resistance of a superconductor circuit element undergoes a sharp variation around Tc (Esp 2) The relation between resistance and temperature for a superconductor around Tc is then experimentally explored (Esp 3) With the help of an oscilloscope or on-line sensors, the potential difference at the extremes of various circuit elements containing at least one superconductor is measured (Esp 4superconductor switch) The measurement of the current in the various segments of these simple circuits, in particular in the segment where the superconductor element is present, allows the critical current, above which the superconductor returns to the ordinary conducting state, to be determined (Esp 5) A simple apparatus, consisting in a variation of the experiment 1, allows a Maglev to be simulated, accounting for its functioning (Exp 6) 11 CLOSING REMARKS The results of the experimentations, comprising the analysis about the student learning, allows us to assert that the superconductivity can be introduced in secondary school at different levels and with differentiated approaches (RQ1) The main objectives of the 17 evaluated experimentations (more than 350 students) show that concepts considered important by teachers have been learnt by 80% of students The effectiveness of the experimentations concerns the following elements: the paths, differentiated by context and age, have been designed so as to adapt to the classes, the common working methods, the teacher working styles; the offered materials have shown to be effectively integrable in differentiated approaches; the teachers, mostly expert and not novice to experimentations, have been able to improve the SC2 proposals with personal contributions, especially on the experimental part The open knot is how to translate the wealth of the SC2 experimentations into different contexts, since, from the curricular point of view, they offer useful indications for didactical paths For a Scientific Lyceum the best choice seems to focus the didactical setting on the field lines, since, in addition to being naturally integrated with the programs traditionally followed in this kind of school, it results qualifying for the formation in the students of a formal and cultural thinking in general In particular, it is important that such approach comprises a necessary detail and specification for what concerns the field representation For students of the first two years or for those without much deep physics courses, it seems worth an approach through the resistivity that comprises the use of field lines with an iconographic representation of the fields (RQ2) The following topics are particularly significant, since they integrate both with most traditional programs and with the paths proposed for SC, offering the opportunity to plan effective curricular renovation: B1 Material characterization (metallic, semiconductor and superconductor or insulating) in terms of resistivity as a function of temperature B2 Electrical properties and thermodynamics of conductors with increasing input power (e.g.: the filament of a lamp with varying of the supply voltage) B3 Electric and magnetic phase transition related to the carrier concentration B4 Microscopic and analogical models of the electric properties of materials – of the conduction (band model, structure model, free electron crystal model, energy levels model) (RQ3) The CD – SC presents the various themes with a prevalently qualitative approach, with good simulations, as recognized by all teachers The lack of the quantitative part, even if it appears a limit as to be considered more appropriate for the first two years, has the great advantage of being very versatile, as observed about the effectiveness of the experimentations (RQ4) The employability in very differentiated contexts with effective results on the learning paths indicates that the multimedia instruments have to exhibit a modular structure where it must be: - different levels of deepening and representing the problem, with photographic reproduction and consequent schematization; the process/experiment, with the video and the eventual simulation; its observations, with representation of eventual data and graphs - different levels of formalization (on one side: construction of categories and clusters of concepts; iconic representation of properties – on the other side: relevant variable individuation; correlation recognition; linearization of problems and relation construction) The experimenter teachers, often spontaneously have found that the best is the use of an integrated methodology where the simulations support the laboratory, without substituting it Acknowledgements Thanks to the teachers who conducted the experimentations G Bertoni, M Braida, M Buganza, V Capocchiani, C Cavallo, F Ciralli, N Cutuli, V De Lillo, C Distefano, R Fiore, C Gianino, M Giacobazzi, B Giardullo, G Giovanazzi , M Gnech, D Gottardi, S Monfalcon, W Manzon, R Sangoi, F Zanon, and their head-masters, DIFA and CIRD of the University of Udine for the support in the experimentations coordination and the responsible of the European projects Vegard Engstrom REFERENCES 12 Aiello Nicosia, M.L et al, (1997) Teaching Mechanical oscillations using and integrated curriculum, International Journal in Research on Science Education, 19(8), 981-995 Bransford, J.D., Brown, A.L and Cocking, R.R (Eds.), (1999) How People Learn: Brain, Mind, Experience, and School, Chap Teacher Learning, National Academy Press, Washington, D.C 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(2000), Research on Teaching and Learning Quantum Mechanics, papers presented at the Annual Meetings NARST, at www.phys.ksu.edu/perg/papers/narst/ AFFILIATION AND ADDRESS INFORMATION Federico Corni Physics Department, University of Modena and Reggio Emilia, Italy Email: federico.corni@unimore.it Marisa Michelini Email: michelini@fisica.uniud.it Lorenzo Santi Email: santi@fisica.uniud.it Alberto Stefanel Email: stefanel@fisica.uniud.it Rossana Viola Email: rossviola@yahoo.it Physics Education Research Group of the Physics Department University of Udine Via delle Scienze 208, 3310 Udine 14 ... analyze the various projects according to the following common elements: the experimenter teachers attended the same training (Michelini et al 20 08 b); the CD-SC proposals were included in all the. .. Institutes (Disint et al 20 08) An approach, as illustrated in the following, that integrates the exploration with the understanding of the concepts, brings the didactical potentialities out THE. .. phenomenon The field produced by these induced currents, in this case has the opposite verse of the inducing field and then is responsible for the evident slowing down of the falling magnet The experiment,