196,095 research outputs found
Le difficoltà degli studenti in Teoria degli Spazi Vettoriali viste da due prospettive teorche diverse
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Semiotic mediation within an AT frame
No full textThis article is meant to present a specific elaboration of the notion of mediation in relation to the use of artefacts to enhance mathematics teaching and learning: the elaboration offered by the Theory of Semiotic Mediation. In particular, it provides an explicit model – consistent with the activity-actions-operations framework – of the actions which are expected from the teacher in order to make mathematics learning occur through the mediation of an artefact. The teacher’s actions are identified by their goals and are related to the motive of the teaching-learning activity
L'attività di risoluzione di problemi come motore dello sviluppo della competenza matematica
No full textDopo una breve riflessione sulla natura dell'idea di competenza matematica e di problema e del ruolo che in un approccio tradizionale all'insegnamento della matematica i problemi rivestono, l'articolo esamina come l'attività di risoluzione di problemi possa promuovere contestualmente lo sviluppo da parte dell'allievo di conoscenze e abilità di base in matematica insieme a forme si pensiero più sofisticate. La discussione attinge a esempi di attività didattiche sviluppate nel contesto dei progetti "Matematica per il cittadino" e "M@tabel
STRAITGH ON THE SPHERE: MEANINGS AND ARTEFACTS
No full textThis report is drawn from a teaching intervention which aims at introducing spherical geometry in a primary school. Assuming a perspective according to which learning should involve students in processes leading to the explicit formulation and elaboration of meanings, this report is meant to explore the dynamics between students’ elaboration of meanings emerging from an activity with artefacts and students’ explicit reflection on the use of the artefacts themselves
Il problema del raccordo Scuola Superiore - Università
No full textIn a moment when few students enrol in courses within the Faculty of Science, the problem of first year undergraduates’ difficulties in mathematics has become a social issue. The main consequences for students are a delay in graduating and, sometimes, the feeling that they made the wrong choice. Lately, a number of initiatives have been undertaken by both the Ministry and the Universities in order to stem this phenomenon.
In this paper, we look at students’ difficulties in mathematics from a perspective that is opposed to that viewing the only origin of these difficulties in students’ lack of preparation. Our “alternative” interpretation guided us in the design and planning of preliminary courses that have been organised over the past five years by the University of Pisa’s Faculty of Science and set up by a working group including both the authors. We will try to account for the specific nature of these courses through a description of objectives, part of the original materials produced and used during the sessions and methodology underlying the actual development of the session
Le difficoltà in matematica nel passaggio Scuola Superiore - Università: dalla teoria alla pratica
No full textExperimental and Numerical Characterisation of the Mechanical Properties of the Titanium Alloy-lightweight Concrete Interface
No full textQuesta tesi affronta la possibilità di utilizzare il titanio come materiale alternativo per il rinforzo del calcestruzzo dal punto di vista del comportamento di interfaccia che i due materiali sviluppano quando sono combinati in un materiale composito strutturale. A tal fine sono stati condotti diversi programmi sperimentali: prove di sfilamento (pull-out) di barre lisce in lega di titanio Ti6Al4V da provini di calcestruzzo di peso
normale (NWC) e alleggerito (LWC); prove di pull-out di fibre in Ti6Al4V dritte ed uncinate alle estremità da provini in LWC; prove di flessione su tre punti su provini e su una trave di dimensioni realistiche in calcestruzzo alleggerito fibrorinforzato con fibre di titanio (TiFRC). L’ultimo programma sperimentale è volto alla caratterizzazione della resistenza alla frattura e alla quantificazione dell’effetto scala sulla resistenza a flessione. Le prove di pull-out sono state supportate dall’analisi numerica. I risultati dei test condotti sulle barre in lega di titanio, coadiuvati da analisi al microscopio elettronico (SEM) e ottico, hanno evidenziato che, nonostante le barre impiegate siano lisce, il processo di sfilamento è influenzato dalla formazione di asperità all’interfaccia, dovuta prevalentemente alla presenza di materiale matriciale residuo sulla superficie delle barre. La rottura di tali asperità genera un ingranamento meccanico a livello microscopico, a sua volta responsabile del comportamento dilatante dell’interfaccia. Per descrivere numericamente questo processo è stato formulato un nuovo modello coesivo definito enhanced degrading M-CZM, che tiene conto dell’azione di danno, attrito, ingranamento meccanico e dilatanza. Con tale modello, sono state condotte analisi di sensitività e una procedura di identificazione per riprodurre i risultati sperimentali delle prove di pull-out delle barre. Un’ulteriore validazione del modello è stata ottenuta simulando numericamente le prove di sfilamento delle fibre dritte.The possibility to use titanium as alternative reinforcement for concrete is investigated in this thesis by focusing on the interfacial behaviour that the two materials develop when they are combined in a composite structural material. To this end, several experimental programs were conducted. The first one concerns the pull-out behaviour of plain bars made of the titanium alloy Ti6Al4V from two different concrete mixtures, i.e. Normal and Light Weigh Concrete (NWC and LWC, respectively). The second experimental program investigates the pull-out behaviour of Ti6Al4V straight and hooked-end fibres from LWC specimens. The third and last series of experiments regards the fracture toughness characterisation of a fibre reinforced concrete material made of LWC and titanium fibres (TiFRC). A series of specimens and a full-scale beam made of TiFRC, without any other reinforcement, have been built and tested under three-point load conditions in order to measure the size effect on the flexural strength. The experimental results concerning the pull-out tests are supported by Finite Element (FE) analyses. Particularly, the results of the bar pull-out tests, combined with Scanning Electron Microscope (SEM) analyses, show that, although the employed rebars are plain, the debonding process is strongly affected by defects-induced surface roughness present at the microscopic level, which activates mechanical interlocking responsible for the dilatant behaviour of the interface. A novel cohesive zone model micromechanics-based formulation is implemented in the FE model in order to account for such aspects. The introduced enhanced degrading M-CZM, accounting for damage, friction, mechanical interlocking and dilatancy, is used to carry out sensitivity analyses and identification procedures on the FE models simulating the bar pull-out tests. The proposed modelling strategy is further validated by performing FE simulation of straight fibres pull-out tests
The secondary-tertiary transition: beyond the purely cognitive
No full textTransition from secondary to tertiary level is an important issue in mathematics education, indeed this transition is often problematic for many students. University spontaneously reacts through running bridging courses, lowering the level of the mathematics taught, or reducing the examination standards in order to avoid massive failure. For different reasons these reactions rarely proved to be effective. Instead, research in mathematics education highlights that students’ difficulties are related to a multiplicity of factors – cognitive, meta-cognitive, affective and linguistic – the incidence of which is amplified when accessing tertiary education. Starting from these findings, the authors designed and developed two parallel mathematical “university preparatory” courses for grade 12-13 students
Semiotic mediation and teacher's actions
No full textActivity Theory (AT) can be regarded as a “multi-voiced” theory (Engeström, 1999; Kuutti, 1995): a framework gathering together a number of different studies carried out by researchers across the world and from different disciplines, that develop at different levels a core of shared “ideas” or “concepts” – the hierarchical structure of activity, and tool mediation among others – whose original initial expression and elaboration can be found in the studies of Vygotsky (1978) and Leont’ev (1964/1976). We will discuss a specific elaboration of the notion of mediation in relation to the use of artefacts to enhance mathematics teaching-learning with a specific focus on the teacher’s actions
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