CONCEPTUAL LABORATORIES OF OPERATIVE EXPLORATION (CLOE) TO BUILD FORMAL THINKING IN BASIC SCHOOL: THE CASE OF SOUND Sri R. C. Prasad Challapalli, Marisa Michelini, Alberto Stefanel Research Unit in Physics Education, University of Udine Abstract The design of innovative didactic sequence on a specific topic requires, in the Model of Educational Reconstruction perspective, besides the conceptual contents reconstruction, knowledge of students' conceptions about the topic focused. Conceptual Laboratories of Operative Exploration (CLOE) were designed with the goal of gaining direct knowledge on how students, particularly younger children (kinder-garden, primary, middle school), approach to specific topics and to the operative proposals, through which the innovative educational proposals are developed. CLOE lab involves pupils to discuss everyday life scenarios, recover their everyday and sensorial knowledge, explore experimental situations by means of Inquiry-Based Learning strategies. The informal learning environment of a CLOE session is an ideal format also for the research focused on students’ ideas and reasoning patterns, how they build formal thinking, develop interpretative representations, construct models on phenomena, reinterpret everyday knowledge. The research design characteristics of the CLOE labs are presented, exemplifying it, in the case of sound in primary. Key words: primary students; learning path; informal learning. 1. Introduction. Researches carried out according to different perspectives pointed out that the common-sense ideas about physical phenomena are formed at the very early stages, the sensory experiences, daily as a result of the interaction of children with phenomenal reality [1-3]. These concepts are developed mostly in an unconscious way and therefore emerge as difficulties in learning a coherent scientific view of the phenomena, when coexist with scientific concepts and models [4-7]. It is necessary to make these ideas explicit and they become the background on which the pupils start to explore the phenomenology, activating the conceptual change to be considered in planning teaching strategies on different topics [8-14]. It is therefore, a necessary, to have a thorough understanding of what sort of concepts and ideas the students possess before taking up a specific topic, in which contexts of everyday life they place and identify/recognize, what type of conceptual processes are activated when addressing a specific phenomenology, what kind of ideas they construct [15-17] and their role on learning process [10, 18-19]. In the Model of Educational Reconstruction (MER) perspective [20], the design of innovative educational sequence on a specific topic require both the reconstruction of the basic conceptual contents as well as the knowledge of students' conceptions about the specific topic [3,18], intension with which students give meaning to the concept explored, its extension that involve the phenomenological contexts in which it is placed by students [21,22], the conceptual paths [13,23] they follow when dealing with different crucial steps of the proposal. Conceptual Exploration of Operative Laboratories (CLOE) were designed with the goal of gaining direct knowledge on how students, particularly younger children (kindergarten, primary and middle school) approach to specific topics and to the operative proposals, through which the innovative educational proposals are developed [21]. In this paper we initially discuss the general design of the CLOE labs, and then in detail about the case of sound and the results emerged. 2. The CLOE laboratories: research tools in informal setting The core of the CLOE Labs consist in semi-structured interviews, in the context of experimental exploration activities with children of kindergarten, primary or middle school, preceded and activated by a group discussion and integrated with some Rogers-type interviews [24-25], used to go deeper in the analysis of students conceptions. We performed CLOE labs studies on schemes of representations of reality and to interpret reasoning sequences during learning activities on different topics: such as thermal phenomena; [26], magnetic and electromagnetic phenomena [27-28], free fall and gravitation field [27,29], electrostatic phenomena [30], electric and logic circuits [31], energy [32] and sound, which here is, considered and discussed in detail. As a context of research, the CLOE labs aim to explore in an informal learning setting, the contribution of practical and conceptual operativity to the learning of basic concept in physics and to the construction of formal thinking. Each thematic lab focalizes on specific research questions, concerning three main types: RQ1) intension and extension of student conception about a specific concept (i.e. energy, thermal equilibrium, magnetic field) or phenomenological area (i.e. magnetic or thermal phenomena) [21,22]; RQ2) learning knots related to the topic explored [3,18]; RQ3) students learning paths [13,23], interpretative models [1-2,5,33], and causal reasoning [34] activated by the discussions and the manual and conceptual exploration activated in the CLOE lab [21]. In a typical CLOE lab session, lasting 1 h or 1 h and half, a researcher interact directly with a group of students in the following three main phases, organized in different setting according to, the topic focused, the main objectives of the research performed, the age of students. During the 1st phase, to explore the research questions mainly of RQ1 type, pupils, individually first and then in large groups, are involved in different explorations, depending on the specific design of the thematic lab: a) analysis of everyday life scenarios, as in the case of the CLOE on thermal phenomena [26], activating and sharing their recall on personal experience concerning the topic faced and discussing on the (scientific) concept expressed in common language (i.e. meaning of to be hot, to feel hot, to keep hot, to become hot; meaning of conserve, lost, transform energy [32]; b) preliminary interview on general questions concerned the topic explored, as for instance in the CLOE on magnetic phenomenon which is commenced by asking the children what they know about the magnetic phenomenon [27-28], to enable the recovery of their everyday life experiences, or the lab on energy in which, children, in the written form or in form of an interview respond to a questionnaire of seven questions regarding the knots dealing in the same lab (what they know about the energy, are there things making/having energy, energy is conserved and what it means to be conserved in this case, the energy is transformed/lost/is transmitted with related examples [32]); c) exploration to answer a specific question (i.e. in the CLOE on sound: how to make sound with each of the objects posed on a table) of a concrete/real scenario including objects able to activate all the conceptual knots that will be focusses in the successive phases of the lab, and discussing with pupils and sharing their answers, collecting their spontaneous observations on phenomena and specific processes recognized, their questions, recalls of their personal experiences activated. The 2nd phase aims to address the research questions of type RQ2 and RQ3. Pupils are directly and personally involved, in either little groups or individually, in the analysis of experimental situations, proposed with an IBL approach [33, 35] and following the questions and the problematic situations suggested by pupils itself in the first phase of the lab. We study from one side the conceptual processes of pupils and the interpretative models activated by interaction with the simple apparatuses, from the other side we analyze how pupils use the conceptual instruments they construct step by step in the lab itself in the analysis of the successive steps. Each steps of the CLOE Lab is proposed with an experimental proposal realized with simple materials (and on-line sensors in the specific case of CLOE on thermal phenomena, and is focused on a specific learning knot. In all the labs, the researcher can select, at each step, the appropriate experiment to propose to the students disposing of a set of proposals that were set up previously and designed according to a coherent educational path, that constitute at the same time, reference for and object of research in the CLOE lab. The 3rd phase involves pupils in resuming and making explicit their learning at the end of the lab, in a written way with short sentences and (or exclusively in the case of kindergarten children) schematic drawings of what they have done and learnt in the lab, or construct a conceptual map of the concepts explored, or more systematically resuming the main activities in the lab specifying action/observation/conclusion. The aims of this phase is to collect documentation on which give answers to the research questions RQ2 and RQ3 types for what concern the phenomenological aspects mainly quoted and connected by students to their learning, the structure of the concepts learned, the concepts or the link between concepts remained open, the models developed and from which starting nuclei these models are developed. The CLOE labs, and in particular the 2nd phase, are based on an interview protocol, designed according to the specific research questions focused for the lab itself and on the educational proposal of reference. The interview protocol constitutes just a plot for the researcher, that carry out the lab following the suggestions of the pupils, focusing to the a priori research questions stated for each step of the lab. Usually the 1st phase of the CLOE lab indicates the line for the core of the lab, in particular, suggesting to the researcher conducting the lab the contexts more familiar to the pupils and the problematic knots that they feel interesting to explore, because activated by our stimuli. The way students respond to our (not neutral) stimuli is also subject of research. 3. Research design of the CLOE Lab on sound Research on learning processes on the sound was particularly focused on students of middle and high school and college too, for what concern conceptual issues related to the propagation of sound. It has been shown that students often see the sound as a material entity that propagates with a particle-like modes [36-41], or as a transverse perturbation rather than longitudinal [42]. It was also revealed that students have difficulty recognizing and conceptualizing the factors affecting the speed of sound, to identify and distinguish the characteristics of sound, such as height pitch, intensity, timbre [43-44] and to fully identify the processes underlying the production and reception of sound [45-46]. Partially positive learning outcomes have been highlighted by activating capacity for argumentation and modeling, in particular with the use of ITC in this area [45, 47-49] and different strategies to promote conceptual change [50]. The didactic proposal for primary school, which was the reference for the CLOE on sound [51], is based on recognition of interaction at the base of any sound. It proposes the exploration of simple experiments for recognition of vibration as a mode to produce, transmit, and receipt the sound. In particular, it stresses the need for the medium (fluid or solid that is) to allow the transmission of the sound itself, and the role that the pressure variations in the propagation of the sound in air. Finally, it includes the recognition of the characteristic properties of sound, in order: intensity, pitch, timbre. This path has been tested in a pilot class of primary school and, appropriately modified and adapted, in four kindergarten classes. A future publication, reflecting our work will refer to a complete illustration of the education proposal and the outcomes of experiments based on it and conducted by teachers in the classroom. To develop the proposal on teaching sound in vertical perspective, there is the trouble to study the conceptual processes activated in children from operative proposals, investigating in detail how children deal with the different knots, what are the steps by which they exceed and the contexts in which this happens, what are the models that they activate spontaneously and how these can be modified to enlarge their range of coherency. To this end, it was designed a CLOE lab on the sound. In this lab children are involved in the exploration of the following aspects: ways to produce a sound / noise with common objects, as well as small musical instruments, nature of the sound as perturbation that propagates in the media, characteristic of a sound (intensity, pitch, tone, and duration). The CLOE lab develops through a sequence of experiments, each focused on a specific conceptual knot, which is offered to children as a game, challenge the plans of doing, observing, of interpretation come into play with different weights depending on solicitations of children involved in them. The methodology used in the CLOE labs on sound was to construction of a concept in an operative way and monitor how students use this concept facing a new problematic situation. The sequence of conceptual knots faced in the CLOE lab on sound are: A) at the origin of any sound/noise there is the interaction between two systems; B) this interaction can occur in different ways (beating, rubbing, plucking, blowing, by banging an object against another); C) an object must vibrate to make sound/noise; D) the different modes of vibration of the same object is the basis of the fact that it can produce a sound, or a noise; E) the sound is propagated: in all directions; connecting directly source and receiver in an homogeneous media; through different systems, whether fluid or solid; F) the main properties of sound are: intensity, pitch, duration and tone. This sequence of the knots is not followed rigidly, but rather is appropriately adapted and modified according to the conceptual pathways that children follow them, being able to draw on a rich set of materials and operational proposals appropriately designed experiments that allow us to look at different knots from different perspectives or in different contexts, or facing a specific way in which there might be a learning problem. Here we present the experiments referred to, by the subsequent analysis of data on conceptual paths of children involved in the of CLOE lab on the sound and related to the first three knots A)-B)-C). A brief indication of how they were proposed and for each the specific research questions that are focused in the laboratory sessions will be also presented. Exp. 1. As discussed in the previous paragraph, the 1st phase of the CLOE lab on sound is implemented with an operational proposal aiming to address the conceptual knots A) and B), and at the same time to present, while not explicitly, the entire overview of the aspects that we would face in the sound laboratory. A counter full of objects is presented to the children: Fig. 1 A set of object is putted on the table: how each of them can make sound/noise? some pot lids, metal and wooden spoons, balls of different sizes and materials, a cymbal with its hammer to strike it, a few pieces of wire, some ribs, two large plastic pens, some blocks of wood the same shape but different size, a string, a rubber band, a plastic bag, bicycle bells, metallic bells of different sizes, a piece of foam, a toy guitar (fig. 1). The first question posed to the children was: " how to make sound/noise with each of these objects?”. Different ways of working have been followed: exploring object to object, challenging children to find as many ways to make it do sound/noise, offering children a free initial exploratory phase in which they were set free to touch objects, trying to make them to make sound/noise. The way each child identified to make sound/noise, the systems quoted, the expressions used and eventually the sketch they draw to refer to the outcome of their explorations are monitored to answer to the following research questions: A1) which and how many different ways are found to make sound/noise with an object, A2) identification of the two interacting objects producing a sound, A3) ways to report phenomena and processes (according to a local vision and contingent restricted to specific tests done, according to a global point of view on the process by making such a reference to the concept of interaction between two objects /systems, according to the two different levels, with examples of tests done and their generalization, A4) aspects that are spontaneously recognized and fielded by children, for example about the properties of sound, the nature of disturbance that propagates. Exp. 2 To explore the third knot, i.e. to recognize that to make a sound/noise an object should vibrate, typically, the game, to hang a pot cover (or a cymbal) and hit it with a spoon or a little hammer was used. Children experienced what they perceive to touch lightly with their finger on the edge of the cover and were made to report the sensation experienced (fig. 2). To recognize the conceptual basis of the distinction between sound and noise (knot D) then it is proposed to repeat the experience of holding the lid with their hand immediately after the sound production. In a similar way has been Fig.2 The cymbal produce sound vibrating proposed to explore how a bicycle bell rings. Children were requested to report in words their sensations and often illustrate also with a sketch the situation, focusing on the following research questions concerning the knot B): B1) the phenomenon of vibration: the ways in which it is described/represented/explained and how this phenomenon is related to the interaction that produced it, B2) the ways in which it is recognized/described/explained that the vibration is the way in which the object made sound, B3) in how many cases and in what ways the chains of causal connections behind the phenomenon were reported (percussionvibrationsound). Exp. 3 With the same aims, to the children was proposed to explore how make sounds and noises with their own body, by monitoring: C1) the ways proposed and explored by children, C2) individuating if the use of their own body activates the recognition of new ways to produce sound. Exp. 4 In the CLOE lab the problem of sound propagation was considered from what concern these different three aspects: 4a. Sound propagation in all directions, proposed asking the children to raise their hands when they heard the sound of a pot cover or a cymbal when struck at the center of the room, initially from near and then from far or when departed: 4b. sound production, propagation, reception are due to the vibration of source, medium, receiver, analyzing the models of pupils when they explore the situation illustrated in fig. 3 and where pepper seeds put on a membrane jump because of the vibration of it cause the sound produced by the tambourine and transported by air vibration; 4c. the sound propagation occur in air and in other kind of (solid or fluid) materials, Fig.3 The pepper seeds jump on a membrane vibrating cause the sound produced by the tambourine and transported by air vibration. analyzing the pupils models when they are request to illustrate “how they had been able to hear the sound” of a diapason or a cymbal produced by the teacher outside the lab. To collect the models of sound propagation in the three situations, pupils where request to illustrate with a sketch how they can give an explanation of the phenomenon explored giving also a brief comment in word explaining the figure realized. Research objectives that were identified for these activities are: D1) phenomenological aspects predominantly identified; D2) how they represent the sound, its propagation, its path of propagation and the related interpretative/descriptive models; D3) ways of representing the sound inside materials; D4) processes that are recognized at the base of the phenomenon and the causal chain of processes. 4. Monitoring tools, methodology of data analysis and context The focus of the work presented here is, on the ways how students represent sound and process they individuate at the base of production of a sound, the majority part of data are collected by open work sheets where pupils report their representations and comments on it, their conclusions on the exploration made in the lab. These data are crossed with those emerging from the transcriptions of audio recording of the lab; notes written by researcher, micro interviews at the end of lab sessions with single pupil to collect case studies and more information on representation made. The analysis has provided an initial phase of identifying categories that were identified a priori on the base of the research questions and a posteriori redefined, with identification of representative examples and case studies and a subsequent evaluation of the frequency with which the different categories have emerged and analysis of the distributions obtained. The data were collected during the events Mediaexpo 2010-11 organized by the Comprehensive Institute of Trescore Cremasco, in CLOE lab sessions lasting 1 h in a classroom/laboratory where the experimental proposals were available to the direct use of children participating to the session. The entire sample of children with which has been conducted the search is summarized in Table 1. In the follow, the number of sub-samples considered from time to time is specified. TABLE I. Students, classes, schools involved in the CLOE Labs on energy in Crema (2010/11) Grade N students N classes 3 30 2 4 166 8 5 37 2 5. Analysis of the concepts developed by the children and their representative models The findings from the analysis will be present and discuss by referring to the conceptual knot explored and the specific experiment which has been explored with the children. 5.1 How do you make a sound / noise? In Figure A, the graph shows the categories of responses obtained from the entire sample students (N=233) with respect to the question: how to make noise/sound (how can you make noise/sound?). In the first three categories, including 75% of the sample, the answers explicit that at the base of the interaction of producing a noise/sound is some kind of interaction between two objects: doing a local reference to some specific interaction between two objects actually used in the CLOE laboratory (Cat. C - "beating a lid with a spoon", "rubbing two covers"), recalling a specific interaction in this case, referring it to two "objects" generic (cat. B - "beating two objects"), referring explicitly to the need to interact two objects (cat. A "should be hitting things, beat them against another object, pinch them, rubbing them, striking them, that is interact"; "To make a noise you shake an object, an object is rubbed against another, you pluck it, you slam it on the table, in short, they do interact"), evidencing the passage from a local vision of the examples to a more general one where the concept of interaction synthesized all the specific particular cases. Fig. 4 Categories of the typical answers to the question: how to make noise/sound (N=233): A) to make interact two objects, making explicit the need to have two objects in 7% of cases; B) by “beating” / “rubbing”… “two objects”; C) specific examples (beating a cover with a ladle; rubbing a plastic bag with hands); D) by “beating / rubbing”…one object or simple “to beat”, “to rub”… In the responses included in the minority category D, students refer just to an action, at best made on an object (Cat D "rubbing", "beating a cover") does not explicit any other object. Concerning the number and types of verbs/actions mentioned the distribution obtained are reported in Fig. 5, where 2.6 is the average number of actions/verbs quoted, resulting in 41% of children having indicated just a single action, in 37% who have given 2-3 different, over 20% that indicate 4 or more (up to 7). The most commonly, indicated by ‘80% of the sample, is to beat (cat B graph of Fig. B). Other ways to obtain sounds identified are by rubbing (i.e.: two objects or a bag with the hands) (46%), plucking (a string, a guitar 22%), throwing an object on the ground or against something (12%), blowing in (a flute, a harmonica) (12%), making an object vibrate (15%). Beating is also the typology of interaction more quoted by students on how make noise/sound with their own bodies (clapping hands 75% or beating with foots the floor 62%). Whistling (43%) and singing (18%) are the more quoted modes, evidencing a more frequent reference to modes involving directly the vibration of air to make sounds than in the case of exploration with objects. Fig. 5 Way to produce noise/sound: Number of verbs/actions quoted and more frequent typology quoted (N=233): A) Beating; B) scrubbing/stretching; C) Throwing; D) plucking; E) blowing; F) making vibration; The picture that emerges shows that a large majority of children focalized explicitly on the role of the interaction between two objects in the production of sound/noise, operating directly with objects and exploring with their body. It emerges also that the action to beat an object against or over another one is the modality activated and recognized in any contexts. The other modes emerge as results of the exploration of specific contexts or of a specific object (plucking a string). The local references are more frequent; being global point of views emerged also from the first phase of the CLOE lab and progressively gained during the lab itself. 5.2 How does an object to make noise / sound? As to the manner in which an object makes a sound/noise, once it has been interacted with another object, the responses were gathered in a sub-sample of 112 children: just after the exploration of the situation; at the end of the laboratory, after exploring at least three other different contexts and having used the concepts of vibration, to report and give account of the phenomena analyzed. In fig 6. are reported the distribution of the three categories emerged in the two collecting phases. Immediately after the first experiment (after exp in fig.6): 73% of the sample (N = 112) was included in the cat. C in which "doing sound" of an object is related to the interaction made on it ("You must knock on the table", "you have to beat two objects together"); 27% has indicated the vibration of the object the way it produces the sound (cat. B - 14% - “cause it vibrates"), reconstructing in half of the cases the processes chain at the base of the production of sound (Cat. A -13% - "You rattle it on an object, and to make the sound you have to make it vibrate"). In all responses, it emerges explicitly and systematically the identification of the two interacting systems, evidencing a change in particular in the pupils included in the previous case in cat D. 80% of cases children have referred to generic objects ("two objects"), while remaining privileged to recall specific actions/verbs rather than the concept of interaction, revealing that the first step taken by the children towards a global vision of phenomena is about the objects with which they are operating, remaining local the reference to actions. A part 5% of the analyzed sample, the answers here categorized A) was given by pupils categorized A) or B) in the previous point, suggesting that the recognition of the interaction between the two objects at the base of the production of sound is preliminary with respect to the recognition of vibration, or, from another point of view, the recognition of the contingent cause (the interaction activating the vibration) for the majority of pupils must come before the recognition of the efficient cause (the vibration producing the sound). Fig. 6 Ways to describe how a body makes a sound (N=112); A) "Beat/Bang two objects, one vibrate" B) "Why does it vibrate" C) "You must beat/bang on something" On completion of the laboratory (after the end of the lab in fig.6), the frequencies of Cat. A and C were reversed (p <0.01 according to the test 2). The vibration of the source object is indicated at the base on how it produces a sound by 73% of the sample. More than half of the entire sample (54% - a large majority of who included in the cat. A) has pointed out the interaction activating the sound because the object "vibrate" or "is made vibrate”. ¼ of the sample (Cat. C), even at the end of the laboratory, associated directly the sound produced by an object only to the interaction. The operative exploration propose in the CLOE lab activated in the majority of children the transition from the operational phase of producing a sound making a specific action on an object, to the analysis of the process of vibration of it. Children of cat. C, just when directly interviewed included the vibration of the object in their description of the phenomena, but they in any case refer on the phenomena linking directly the action made to the result they focalized: “beating on it, it sounds”, “beating on it, it vibrates”. The reconstruction of the causal chain of processes, evidenced in Cat. A) and Cat. B), remained an open knot for the pupils of Cat. C. On the merit of this same conceptual knot, it is particularly significant here to consider the categories in which N = 164 children 4-grade and 5-grade have described the situation of Exp. 4b, when they felt the vibration touching lightly a pot cover percussed with a spoon. Fig. 7 Categories of answers to the question “How make sound the pot cover?” (N=164): A) “If you keep it from below then you feel the vibrations, if you keep it from the border do not feel the vibrations”; B) “Because holding it on to the handle makes a soft noise and vibration, and if you keep it tight makes a dull sound”; C) “tapping the spoon on the cover, it vibrates”; D) “If I slam the cover on the boundary it makes a sound nice, but if I slam on the border it makes a dull sound”. The sentences of children can be grouped into 4 categories (Fig. 7). In the responses in categories A, B and C, which cover 84% of the total sample, the reference appears to vibration of the cover considered here, emphasizing: the sensation of vibration felt by touching the cover, the association of the vibration to the sound ringing ears, the vibration as a result of the percussion made on the cover. The responses of the category D focus on the different sounds made by striking the cover at different points. All types of responses, activated by the inquiry situation in the CLOE lab and showing the different attention of children focused on what surprised them most, has attracted much interest, identify relevant aspects of the phenomenon, even if reconstructing single link (81%) or at most two links (19%) in the chain of processes involved. A complete view, of the connection between the many processes in the analyzed phenomenon, requires a long time activity, where the single elements emerged by each pupil are put together and shared, passing, according to Hara, Bonk, Angeli, from an individual and implicit knowledge to a social and collective knowledge [52]. 5.3 The propagation of sound After the initial phase, during which, the way in which a system produce sound was explored, in some CLOE lab sessions, there emerged the knots: how it is possible hear the sound produced by "one out the door"; how the sound produced in some point can be heard by all. To address these issues and collect the models that children activate on how (and if) the sound propagates, with two small groups of children were analyzed in depth the two simple experiments Exp. 4a and 4b. With a total of 32 children (a 3-grade class and a 4-grade one), in small groups, students analyzed the situation in which the sound made by their teacher outside the classroom with a tuning fork or a cymbal, was perceived by the children in the classroom and evidenced to each other, raising their hand. The children were asked to represent the situation and to explain "how does the sound, produced out of the room, to be perceived by all of us in here”. Fig. 8 summarizes the frequency categories, exemplified in fig. 9, with which the propagation of the sound from the source, through the wall and up the children was represented. The distribution is bimodal type with the prevailing categories representing the propagation of sound: one or more lines that leave the source and arrive at the child/receiver (Cat. A); succession of fronts of perturbation (Cat. D). It can be stressed here that a part of students (12/32) evidenced the ideas of a direct connection from source to hearer using different ways to represent sound, for instance as in the examples of cat A), D), E) reported in fig. 9. Another part (14/32) evidenced a non-rectilinear path of propagation (as the example of cat. B in fig. 9) also using representations with lines or fronts of perturbation (as in the first two examples of fig. 10). The third part of the sample (6/32) shows a not well defined ideas of sound propagation as well the idea of sound as diffuse entity as in the third example of fig. 10. Fig. 8 Categories of representation of sound propagation through a wall (N = 32): A) one or more directional lines from the source to the child recipient; B) a not precisely defined entity that propagate along a curvilinear path; C) indefinite entity not represented in the wall; D) fronts of sound perturbation in form of circle arc which tends to expand with the distance from the source; E) musical notes or letters which propagate; F) representation of the situation alone. Cat A) Cat D) Cat B) Cat E) Cat C) Cat F) Fig. 9 . Examples of the different categories of representation of sound propagation. Most of the children considered here have their own idea of propagation. This idea has a consistent structure enough that they could be considered a model in the case of the different representations in which there is a direct connection source-listener and that was used to represent the present situation as well other ones in the same way. In the other cases, when the direction of propagation is not defined, the same representation is adapted with ad hoc elements evidencing lack of consistency. This is particularly the case of non rectilinear path representations. Figure 10 left and center two different examples of propagation sinuous and right example of the absence of propagation. It was made the hypothesis that the propagation through a not-rectilinear path, as well as the lack of recognition of the propagation of sound could be overcome by activating the recognition that the sound propagates from the source to all directions. This hypothesis has been investigated in the CLOE lab with 22 children (4-grade), proposing the Esp 4a., where the pupils are request to raise their hand when they heard the sound coming from the center of the classroom. As a result of increased exploration is the fraction of children who developed the idea of sound, and indeed a majority of children (13/22) had a second representation of the propagation directions defined. Some representations included the emission of sound from the source in all directions, propagating in two different ways: in rectilinear way directly toward all the different listeners, in a curved way from source to the listeners the part of the sound originally propagating in the opposite direction (6/22), In the remaining cases (3/22) has not found a clear idea of propagation. For this students the representation of sound cannot be independent from the listener (the detector of sound), revealing also the origin of the model of not-rectilinear propagation of sound evidenced in this paper. 5.4 The grains of pepper on the membrane The additional context in which it was explored the problem of propagation of sound was the Exp. 4b, where the vibration of a membrane is activated by the sound produced by a tambourine place in the vicinity and is highlighted by the pepper that there jumps above. In this case, to 130 children from four classes grade-4 and two classes grade-5 were asked to explain the situation and the processes involved, completing the design with a short explanatory sentence. The classification categories identified, built taking into account all the elements explicitly evident in the captions and/or in the drawing, are 5, and Fig. 11 shows the distribution of their frequencies. . Fig 11 A) all the elements characterizing the phenomenon and their causal connections; B) focus on how the source produces the sound and the fact that it propagates in the air; C) only the causal relationship between sound produced by the tambourine and the bouncing of the pepper on the membrane; D) only recognition that the pepper is moved by the vibrating membrane; E) only representation of the objects. The first category (Cat A-13%) include those pictures in which it is reconstructed the whole causal sequence of processes underlying the phenomenon and in particular the recognition that the vibration of the elastic membrane highlighted by the hopping of grains of pepper is activated by the sound perturbation which propagates in the air. The following example illustrates how the concept of vibration plays a central role in the daily processes description: "the skin of the drum vibrates and the vibration through the air passes into the drum and move seeds"). In the category B, the most numerous (53%), the vibration of the air (28%) or the movement of air (25%) activates directly the movement of pepper (the membrane is only considered a support). In the remaining categories, any reference to a disturbance that propagates from the tambourine to the membrane is absent, being only found that the sound produced seeds jump (cat C 10% - "If you beat the drum of pepper seeds to move"), or being recognized that the vibration of the diaphragm to bounce pepper (Cat D 10%), or are only represented the systems involved, and hopefully some of the observed phenomena (cat E-17% "We designed a tambourine slamming the air "). The prevalence of the first three categories of the other highlights that children have correlated sound production with the activation of pepper, including an entity that propagates from the drum membrane and specifically in 41% of cases indicating that entity is the vibration of air produced by the vibration of the drum. 23% of the sample (cat A and cat-D) recognizes that the hopping of pepper is activated by the vibration of the membrane and not directly from the perturbation propagates in the air. Majority was the idea that the movement of the pepper is activated or by the vibration of the air or by the net movement of air caused by the tambourine. When the drawings and descriptions are analyzed separately, it is recognizable that the firsts are more often focused on the iconic representation of sound and its mode of propagation, the second are more often limited to the description of the objects represented and the respective role of the sound source (the drum beaten by the hammer), the receptor (the glass with the elastic membrane), the viewer of the vibration of the membrane (the pepper seeds), as in the two illustrations of fig.12 Fig. 12. Two typical ways to represent the bouncing pepper experiment. 6. Conclusions and implications As contexts of investigation of conceptual processes activated by operativity Conceptual Laboratories of Operative Exploration were developed. These labs consist of semi-structured interviews with alternating stages of discussions to operational phases of conceptual change where an IBL strategy is adopted following an open interview protocol. The researches in the CLOE Labs on children's conceptions, their models activated by stimuli proposed in the CLOE lab provide essential information for the design of innovative teaching proposals on specific topics. Here the general design of the CLOE labs have had discussed and exemplified in the case of CLOE lab on sound. The focus was on the concept developed by a sample of 233 primary students (166 of grade4 and the remaining of grades 3 and 5) on how sound is produced and propagated through media. Data was collected by open work-sheets where pupils involved in the lab individually written sentences on their learn and drawing of the real situations and the process involving sound they explored in the lab with the everyday material, toys and music toys. These data was integrated with those emerging from the interviews. The results of the analysis show that the practical and conceptual operativity enabled in the sound lab CLOE has determined the focus of all children on the interaction between two objects as the way in which it produces a sound or noise. The local reference to the examples explicitly explored (beating, rubbing two covers, two pieces of wood) is the way adopted initially by most children and progressively changed during the lab toward a more global vision, where the interaction between two systems is stressed in a generalized way by the pupils of the sample. The role of the vibration of the system that produces a sound, as well as in propagation and sound reception issues have been more gradually learned by a large majority of children. The recognition that the sound is an entity that propagates is an increasingly consolidated. There are two majoritarian models of representation of propagation: perturbation fronts expanding; propagation through. 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