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Page 1: MAKING PHYSICS FASCINATING TO… - fisica.uniud.it · MAKING PHYSICS FASCINATING TO….. ALL !? Grazia Zini, Laboratorio di Didattica della Fisica, Dipartimento di Fisica, Università

MAKING PHYSICS FASCINATING TO….. ALL !?

Grazia Zini, Laboratorio di Didattica della Fisica, Dipartimento di Fisica, Università di Ferrara, Italia Angela Turricchia, Aula Didattica Planetario, Comune di Bologna, Italia Leopoldo Benacchio, Osservatorio Astronomico, Padova, Italia

1. Introduction

Making Physics interesting to people is a real challenge but worth trying for a number of reasons: many people judge Science and Physics on the basis of information given by media (TV, Internet), information often incorrect, incomplete or just wrong and on these basis they are often requested to judge on Physics aspects that have social impact such as electrosmog, nuclear plants etc.; Physics is perceived as too difficult to be approached by a “standard” student so the number of Physics students is going down steadely everywhere; ……..and also because just trying is rewarding! Our work regards LIGHT. Why light? It is one of the most fascinating physics phenomenon for people of all ages, it is basically interdisciplinary: from arts to all the experimental sciences such as geology, natural science, etc. where Physics of light play a basic role, moreover the visual approach is today of paramount importance (TV, Internet, advertisements....)'.We have developed a complete curriculum [1], based on students activities, which goes from elementary level to university level. The logic of the whole physics proposal is: light as perceived by our eyes vs light as revealed by man-made instruments (spectroscopes, various type of sensors, etc.) in order to present the fascinating world beyond what we see or touch, such as the stars or the electromagnetic radiations beyond the visible range. Here only a section is of the whole work is reported. It regards the use we are making, of a hand-held diffraction spectroscope, produced for Gemmological analysis [2], to introduce visible spectra and to present light as information carrier. Hand-held spectroscopes are not new in Physics education, but this instrument is so simple that it can be effectively handled by pupils about ten years old, and accurate enough to interest University students. Obviously goal, objective, language and Physics level should be suitable to the age of the students. Examples of activities made in classes of ten, thirteen, eighteen year old (and over) students respectively, are here reported. The educational validity of the reported activities were experimented in the last two years with primary school students, with University students, and is also applied to the pre-service and in-service teacher formation. Obviously the activities are integrated in different curricula. We present also the use of the same nice instrument in the interactive section of a museum of scientific instruments [3]. 2. The starting activities

The starting activities are almost the same for all ages and type of audience, a step which takes 2 lessons at least, for pupils about ten years old and just half an hour for high school students. This first step is conceived to stir curiosity, in order to trigger interest. After announcing that the lesson will begin with the study of everyday-life light sources, but without giving further explanation, we put in our students hands a mysterious, nice object :

“What is it ? “ “Try it , look at the white light of the ceiling lamp” “Wait a moment ! White?”. Only at this point we give the instrument name and, when suitable, explain how it works, otherwise we present it only from an operational point of view. The procedure follows : “Use the little spectroscope to look at the incandescent white lamp, at the fluorescent white lamp, at a burning table salt, at street yellow lamps, at the sunlight.

Fig. 1: The hand spectroscope, ruler inserted for length comparison

Page 2: MAKING PHYSICS FASCINATING TO… - fisica.uniud.it · MAKING PHYSICS FASCINATING TO….. ALL !? Grazia Zini, Laboratorio di Didattica della Fisica, Dipartimento di Fisica, Università

Is white light really white?” “And colours? Look at the light transmitted by a red glass, a blue glass, an incandescent blue-light lamp, a mineral, a gem”. Here the second step: surprise which give rise to intentional learning [4].These qualitative activities give operational concepts: of light source, of emission, absorption of light, of continuous and lines spectra. They give the concepts that: • our eyes are limited and might be deceiving: man-made instruments are needed to enlarge our

knowledge ( they too might be deceiving!); light carries information: of the source and of the materials it interacted with, so we have

information on substances which are e.g. too far for reaching ( astronomy), too deep inside a transparent solid to be touched (defects in crystals, material science), too scarce to be perceived by our senses (e.g. elements traces in a mixture Chemistry)........

The teacher role is to foster intentional observation and discussions from which to attain first qualitative report, then quantitative measurement, and to introduce theory at the level suitable to the age and the previous knowledge of audience. For young pupils the proposed experimental activities are intended to make them observe, report, discuss, make assumptions and validate (or not) them by experiment; for higher students the activities are also the basis to main parts of optics: diffraction and the photon model of light. This is the beginning of a learning/teaching process which has been developed in various contexts that use different level of formalisation and of mathematics. We present here examples 1 in astronomy teaching 2 in a lecture to Physics students 3 in the interactive section of a scientific instruments museum, 3. Examples 3.1 An application to the teaching of astronomy The educational procedure for the younger pupils ( 8-13 ys old students) is the one presented in the Project “Cielo! Astronomia e Fisica per la scuola dell’obbligo”, (Heavens!, Astronomy and Physics” [1]. The title contains a little joke, in fact "Cielo!" is used in Italy sometimes in case of surprise). The spectra activities takes about 2-3 hours, and it comes after other simple experiments which enlighten the concepts of source and light sensor, and show that the light intensity transmitted by a number of exposed photographic slides diminishes increasing the number of slides. Important astronomy concepts comes out directly from the “discovery” of the difference between the spectra of the light from an incandescent lamp and the sun, followed by the observation of the flame produced by a burning table salt and/or other substances.

Fig. 2: A report in the lab-book of a ten year old child ( “Elementari” school, Bologna, Italy)

Fig. 3: Observing the flame of cooking salt

In fact each pupil (without support from teacher) is able to see, with the little spectroscope many Fraunhofer lines superposed on the continuous spectrum and a very bright line on second case ( only one, elas!). Discussion on these effects with the whole class and the use in class of an applet

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[5] which displays the emission and absorption spectra of the periodic table elements, make students understand how astronomers are able to deduce the composition of the stars “without going to them”. The Sun emission spectrum induces also understanding of the Earth atmosphere effect on the light which reaches the Earth. [Other experiments, not in Cielo! Project, are now available to deepen the understanding of the effect on light by other stars atmosphere[6]]. Experimentation on this activities were made during 2000/2001, in “Elementari” schools (about 650 pupils, 9-10 year old ) and “Medie” schools (about 150 students, 12-13 year old) [7]. Activities were in part made by the class teachers working alone, in other cases researchers were active in class during the lessons and other times the students do the activities during a visit to the "Aula Didattica Planetario" of Bologna. Spectroscopes and written material about the lesson procedure were given as support to the teacher. In-service teacher formation was adopted in some cases, other teachers were able to proceed by themselves with little help, by e-mail or phone, from Physics education researchers. Evaluation of the proposal were obviously made in the usual way by written tests, open-end-question to students and discussions with students and teachers. The results were very good. Here we report the phrasing of one of the teacher: “The results are clearly positive for my students who took part with enthusiasm to activities and discussions. From my point of view I liked very much to teach Physics in this way; it is perhaps the first time I liked it so much” 3.2 Application in Physics lessons at High school, University and Teacher training The activities outlined above were proposed also to students at the beginning of their University carrier (17-20 ys old students), both Physics and non-Physics students and also to in-service and pre-service teacher training [8]. The approach was almost the same as above, only the playful procedure takes less time ( about half an hour ) and it is followed by the theory with the appropriate mathematical level.

Fig 4: High school student using the spectroscope during a visit to the Physics Dept. of Ferrara

Fig 5: The “blackboard”at the end of a lesson to

Physics students (Dept. of Physics- Ferrara ) The spectroscope was first used to display the spectrum of helium-neon laser light, and to discuss diffraction phenomena and related theory. Then the observation of line spectra made easy to introduce ( or revise) the photon theory. For non-Physics students an applet of a photon interacting with an Hydrogen atom [9] proved to be very useful to the understanding of the emission-absorption model. The experimentation of the Physics educational proposal here presented, took place during the last two years at the Department of Physics, University of Ferrara. It involved students of “Diploma di biotecnologie agro-industriali” (non-Physics students), Physics students of the first year course and students specializing in Physics teaching (a two year, post degree course which must be followed by all future teachers). The qualitative approach revealed to be particularly important since very few student in Italy have Physics in their pre-University studies and so lack of the qualitative appraisal

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of the Physics phenomena, which in my opinion, is necessary when studying a Physics phenomenon for the first time. 3.3 Application in an interactive section of a scientific instruments museum

La sezione museale:

9 oggetti : prismi, reticoli, banco di Melloni, spettroscopio,

spettrogoniometro. Schede di presentazione per visitatori

con informazioni storiche

La Sezione interattiva: (esperienze ed attività pratiche di laboratorio)

− 12 attività interattive con schede per il pubblico

− 4 esperienze per scuole superiori con schede insegnanti

Fig. 6. Scheme of the museum project composed of history and interactive sections Obviously here the spectroscopes and the educational strategies above explained can be straightforward applied. The Scientific museum visitors are of all ages and scientific knowledge level so the experiments for the younger children are proposed for a public without previous knowledge in Physics, while the higher level approach is for a public with deeper knowledge of science. Working sheets suited for an exhibition were prepared and, obviously, proposal for securing the hand spectroscopes are advanced. 4. Conclusions

The educational strategy here presented links common knowledge to science and shows one example of the role of man-made instruments in Science. Moreover the playful simple practical activities provide motivation for theory, discussion and modelling from a very early age. We can say that the main points of the learning process are:Light carries information

The decoding of light carried information (and its integration in our “Mind” ) depends on instruments used

o Our eyes gives us the first, basic idea of the visual world, that necessary for our life, o Using different instruments we “see” different aspects of “objects” or different

“objects” Eyes, used to observe and analyze, and man-made instruments are for intentional learning [10] (our eyes most of the time are used for not-intentional learning). Intentional learning requires efforts, by efforts we enlarge our knowledge of world from the basic ideas and, doing so, we develop also our Mind. In this way instruments are seen as part of the intentional learning mind. (Mind= brain with its neural web and knowledge acquired) References [1] L. Benacchio, G. Mistrello, M.G. Pancaldi, M.Sasso, M.G. Somenzi, A. Turricchia, G. Zini, “Cielo! Un percorso di Astronomia e Fisica per la Nuova Scuola dell’Obbligo”, Giornale di Astronomia, 4, (2000), 31 (and www.polare.it) [2] http://www.gagtl.ac.uk/sinst.htm#spectroscopes Giornale di Astronomia, 3, (2000), 31“ The Project "Cielo!" is funded by M.P.I. Project S.E.T.: http://www.istruzione.it/argomenti/autonomia/progetti/set.htm