Évolution du sens que les élèves donnent aux mots dans la construction de connaissance relative aux gaz en classe de seconde

National audienceCette recherche s'inscrit dans le cadre d'un travail en didactiques des sciences physiques, s'intéressant aux rôles que joue un enseignement à propos des gaz, sur les processus d'apprentissage des élèves de seconde.Ce travail a été mené en lien avec la conception d'une séquence d'enseignement sur les gaz pour des élèves de seconde. Cette séquence a été réalisée par un groupe de recherche et développement réunissant des enseignants de lycée et des chercheurs en didactique.Pour l'enseignement des gaz, un groupe de 6 enseignants et 2 chercheurs a élaboré une séquence d'une durée de 3 semaines : 3 TP (1h30) et 3 cours en classe entière (1h) (disponible sur le site francophone pégase http://nte -serveur.univ -lyon1.fr/pegase/ et sur le site de l'académie de Lyon http://www.ac-lyon.fr)

A Logical Approach to Efficient Max-SAT solving

Weighted Max-SAT is the optimization version of SAT and many important problems can be naturally encoded as such. Solving weighted Max-SAT is an important problem from both a theoretical and a practical point of view. In recent years, there has been considerable interest in finding efficient solving techniques. Most of this work focus on the computation of good quality lower bounds to be used within a branch and bound DPLL-like algorithm. Most often, these lower bounds are described in a procedural way. Because of that, it is difficult to realize the {\em logic} that is behind. In this paper we introduce an original framework for Max-SAT that stresses the parallelism with classical SAT. Then, we extend the two basic SAT solving techniques: {\em search} and {\em inference}. We show that many algorithmic {\em tricks} used in state-of-the-art Max-SAT solvers are easily expressable in {\em logic} terms with our framework in a unified manner. Besides, we introduce an original search algorithm that performs a restricted amount of {\em weighted resolution} at each visited node. We empirically compare our algorithm with a variety of solving alternatives on several benchmarks. Our experiments, which constitute to the best of our knowledge the most comprehensive Max-sat evaluation ever reported, show that our algorithm is generally orders of magnitude faster than any competitor

Le concept de masse en physique : quelques pistes à propos des conceptions et des obstacles

International audienceCe travail propose de pointer certaines difficultés que rencontrent les élèves lors de l'enseignement du concept de masse en classe. Pour cela, H s'appuie sur l'approche historique de ce concept ainsi que sur l'analyse des programmes, pour bâtir un questionnaire, proposé à des élèves allant de la classe de troisième au DEUG et à des enseignants de lycée. L'analyse de ce questionnaire a permis de mettre en évidence un certain nombre d'obstacles et de conceptions liés au concept de masse, ainsi que de pouvoir suivre leur évolution à travers les différents stades de l'enseignement

Les relations industrielles : un point de vue international

En abordant les relations industrielles d'un point de vue international, l'auteur traite d'abord de problèmes ayant trait aux relations professionnelles dans le cadre de l'entreprise et s'appuie ensuite sur l'expérience des pays industrialisés et plus spécifiquement des pays européens telle qu'elle ressort notamment de la deuxième session de la Conférence régionale européenne de VOIT.In view of the wide differences between industrial relations of the various countries of the world as well as between the political, economical and sociocultural factors which influence them, it might be thought that it is impossible to discern general trends from a comparative examination of industrial relations' phenomena and institutions.This negative reaction, while perfectly correct in many respects, would not however correspond to the whole truth. Almost no country today lives in isolation. Ideas have no frontiers, in so far, of course, that there is freedom of expression. The tripartite meetings convened by the ILO offer a unique opportunity of discovering common problems and trends and their conclusions, especially when they take the form of Conventions and Recommendations, represent an international consensus on important problems of social policy.Trends analysed in this article refer only to labour - management relations at the level of the undertaking and are mainly based on the experience of industrialised countries.THE EVOLUTION OF THE INSTITUTIONAL FRAMEWORK OF LABOUR-MANAGEMENTRELATIONS AT THE LEVEL OF THE UNDERTAKINGSince the Second World War, three main trends have characterised this evolution. A first trend, under employers' influence, has placed the emphasis on the improvement of the social climate by stressing the common objectives which should be shared by all the members of an undertaking, and by seeking ways and means of enlisting the maximum contribution from each towards the common end. This search has been facilitated by advances in social sciences (studies on the motivations of the man at work) and in techniques of management (delegation of authority, management by objectives, etc..)A second trend, essentially of a political nature, encompasses the developments which have changed the basic structure of the undertaking (nationalisations and various forms of workers' participation in the managerial bodies of public or private undertakings). The third trend consists of all the measures which, mainly under trade union influence, are concerned with regulating the behaviour of managements (by law, collective agreements or as result of day-to-day trade union action) in such a way as to curtail their freedom of action by means of a whole series of procedures and institutions. These regulations have resulted in nothing less than a Bill of Rights for workers, which has gradually been evolved to safeguard them in their dealings with their employers.THE CONTEMPORARY TRENDSTowards greater security. In a world which is rapidly changing it is not surprising that the aspiration for security should have become prominent in the industrial relations field. Thus an aspiration towards greater employment and income security is to be noted in most countries. The principle that a worker should not be arbitrarily deprived of his employment has been firmly recognised at the international level, when, in 1963, the International Labour Conference adopted the Recommendation (No. 119) on Termination of Employment, which states that « termination of employment should not take place unless there is a valid reason for such termination ». This is a very important change in comparison with the old philosophy according to which, when a worker has been recruited by an employer under a contract of indeterminate duration, this contract may be rescinded at the will of either party provided a certain period of notice is given.While the recognition of the principle of the justification of termination of employment is essential to ensure the dignity of the worker in the employment relationship, there is nothing demagogic in it. The « valid reason » which may justify termination of employment, may be « based on the operational requirements of the undertaking, establishment or service ». Management therefore remains free to manage according to the best interest of the undertaking. As it is increasingly recognised that technical progress and economic growth need a greater mobility of workers than in the past, security is not therefore synonymous of stability. Certain jobs become reduntant or obsolete. A particular job cannot therefore be protected at all costs. In such situations the trend towards greater security will focus on the protection of the workers' income and on the measures to be taken to facilities his reemployment. While reduction of workforce may be justified as a factor of economic progress, the workers affected by such reductions cannot be left on their own. If society is to benefit from economic progress, it has also to support the social cost of such progress. This is the new principle of social justice which is now gaining acceptance.Towards greater participation. In 1966 the International Labour Conference adopted a Resolution noting that in various countries with different economic and social structures, efforts and experiments are being made to enable workers to participate in the decisions taken in their undertakings and requesting studies by the ILO on this subject. These studies, as well as various meetings organised by the ILO, have shown that while there cannot be an internationally agreed definition of the concept of « participation », workers are anxious to obtain a greater influence on the marking of the decisions which concern them, through methods as different as collective bargaining, joint consultation and communications, or workers' representation in the managerial boards. The concept of participation is likely to dominate the evolution of industrial relations in the next thirty years because the worker of today has new aspirations which are not satisfied by the present industrial organisation. He refuses to be manipulated like a tool or buffeted by forces or decisions over which he has no influence.Towards greater accountability. Twenty years ago it was still an accepted credo in many industrialised countries that the role of government in industrial relations was mainly a passive one: not to interfere in matters which were best left to the autonomous relations of the two industrial partners. When collective bargaining broke, government intervention had mainly an auxiliary character. It was to assist the parties to put the train back on its rails, and not to drive it or to regulate its speed. So long as industrial peace was not seriously threatened, the government was not primarily concerned with the outcome of collective bargaining. Today the parties to collective bargaining can no longer consider that this is their own affair only. Governments in pursuing their economic and social policies are anxious to see the concept of the public interest introduced into the bargaining process. The finding of appropriate solutions is however not easy. The great challenges of our days in the industrial relations field is to determine how the systems and practices should be adapted in order to permit the achievement of public goals without endangering basic human freedoms. The partners to collective bargaining will have more and more to be in a position to justify their behaviour in the light of the public interest.The need for training and education. The complexity and interdependance of problems raised by technological developments and the evolution of economic and social relations call for a tremendous increase in training and education, not only from a technical point of view but also with regard to economic and social knowledge. The International Labour Conference will consider next June the drafts of a convention and a recommendation on educational leave for workers and the Governing Body of the ILO has emphasised the social responsibility of managers as one of the key elements of the future activities of the ILO Management Development Programme. This is all the more necessary that young executives are sometimes challenging the objectives pursued by the companies in which they work

CONTRIBUTIONS OF TALK, GESTURE AND SALIENT ELEMENTS OF THE SETTING TO ANALYSE STUDENT'S IDEAS IN SCIENCE THROUGH VIDEO

International audienceOver the past two decades, video analyses of science classroom have developed tools to describe, model and understand teaching and learning processes. Following the activity theory approach (Leontiev, 1978) using tools adapting from communication analysis (Givry & Roth, 2006), we propose to show what are the contributions of the interplay of talk, gestures and semiotic resources in the setting to analyze students' conceptualization. Our database consists of questionnaires, interviews and classroom video data and written worksheets of 14 students at the upper-secondary school level (Grade 10 [15-year-old students]) during a one-month teaching sequence about gas. We use Kronos software to code videos through several levels : Tasks (Macro), actions (Meso), meaning-making (Micro). Based on semiotic resources contained in language, we reconstruct in great detail all the ideas about gas expressed by students during the entire teaching sequence. Our results show (a) that we need to analyze simultaneously talk, gesture and salient element of the setting to reconstruct the meaning performed by student during communication acts. (b) how the interplay of talk, gestures and salient elements could be pertinent to describe the construction and the stabilization of the meaning of the word quantity performed by a student. However, some research already shows that prosodic features of speech (intensity, pitch, pitch contours) are further semiotic resources used in classroom conversations (Roth, 2005). Future research will show whether and how such additional resources further improve our unit of analysis called ''idea''. Furthermore, our results concern only a few students and cannot be extrapolated. We can considered it as assumptions which will be tested in future research

Studying Students' Learning Processes Used During Physics Teaching Sequence About Gas With Networks of Ideas and Their Domain of Applicability

International audienceIn literature, several processes have been suggested to describe conceptual changes being undertaken. However, a few parts of studies analyse in great detail which students' learning processes are involved in physics classes during teaching, and how they are used. Following a socio-constructivist approach using tools coming from discourse analysis, we suggest studying three processes of students' learning: (1)establishing links between ideas, (2)increasing or (3)decreasing the domain of applicability of ideas. Our database consists of video data and written worksheets of 2 students at the upper secondary school level (grade 10 [15-year-old students]) during a one-month teaching sequence about gas. Based on semiotic resources contained in oral and written language, we reconstruct in great detail all the ideas about gas expressed by both students during the entire teaching sequence. Our analysis deals with (a) how learning processes are identified based on the ideas expressed by students and (b) how the three learning processes are used by the two students during teaching. Our results show that during the teaching sequence: (1) the emergence of the networks of three ideas is supported by networks of two ideas expressed previously by students, (2) both students express more networks of two ideas than networks of three ideas, (3) The process 'increasing the domain of applicability' of an idea or a network of ideas is very often involved and (4) the process 'decreasing the domain of applicability' of an idea or network of ideas is rarely used by them