Dissertations / Theses on the topic 'Multiple representations'
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1
Sniderman, Sarah. "Meaning, multiple representations, computation and instruction." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0003/MQ39419.pdf.
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Cox, Richard Jeffrey. "Analytical reasoning with multiple external representations." Thesis, University of Edinburgh, 1996. http://hdl.handle.net/1842/10550.
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This thesis presents work on analytical reasoning with external representations (ERs) using problems similar to those used in the US GRE college-entrance examination. The work investigates the factors associated with effective ER use in situations where subjects select, construct and reason with their own ERs. Practically all previous work has tended to focus solely upon performance rather than process. In this thesis the emphasis is upon cognitive processes during the entire time-course of reasoning with ERs, from problem comprehension through to answer selection. A background to the work is provided by 2 comprehensive reviews of: 1.) previous research on ERs and reasoning and 2.) the cognitive and semantic properties of ERs. Results from three empirical studies are reported. The first study examined a large corpus of 'workscratchings' produced by subjects as they solved paper and pencil-based analytical reasoning problems under test conditions. The workscratching ERs showed great diversity between and within subjects and across a range of problems. They included lists, various kinds of table, set diagrams, node and arc diagrams, first-order and propositioned logic, plans and natural language. It is shown that problem-solving performance is related to the type of ER used in the solution. The second study utilised a computer-based system (switchERI). The system administered analytical reasoning problems and provided a. range of ER construction environments for the subject to choose and switch between. User-system interactions were recorded dynamically during problem solving. This methodology permitted microanalyses of the cognitive events at each stage during the time-course of problem solving. A process account of analytical reasoning with ERs is developed in which five major stages are identified - problem comprehension, ER selection, ER construction, read-off from the ER and answer selection/responding. A range of common slips and misconceptions are identified at each stage. The results show, inter alia, that subjects whose responses are consistent with their ERs perform better than subjects whose responses are inconsistent with their ERs even if the ER is partially incorrect. The data from the workscratching analysis and switchERI study informed the design of' switchERII, a second system. SwitchERII incorporates a. representation of the semantics of Euler's Circles, dynamically parses the user's representation and provides feedback and advice. A third study was conducted with the switchERII system. Few, if any, studies to date have attempted to relate subjects' prior knowledge of ER formalisms to their reasoning performance. Subjects' prior knowledge of ER formalisms was assessed in both switchER studies. It was observed that subjects' performance on representation interpretation tasks does not necessarily predict their performance in conditions where they select and construct their own representations. The reasons for the decoupling are discussed. Data from all three studies show that subjects often utilise multiple representations in their solutions, either concurrently or serially via. ER switching. Two distinctly different types of switching were observed. One kind ('thrashing') is associated with poorer performance and reflects less comprehensive prior knowledge, inability to select au appropriate ER and hazy problem comprehension. Judicious switching, on the other hand, is associated with high levels of problem comprehension and skilled matching of the ERs' properties to changing task demands. It is claimed that effective reasoning with ERs involves complex interactions between at least three factors: (a.) within-subject variables such as the subject's representational repertoire (prior knowledge) and representational modality preferences (cognitive style); (b.) skill at overcoming a variety of barriers to comprehension and an ability to discern the salient attributes and characteristics of different problem types and (c.) an understanding of the semantic and cognitive properties of graphical and non-graphical ERs coupled with an ability to match those properties to the problem's task demands. It is suggested that the role of externalisation in reasoning with ERs may be to facilitate the swapping of information between cognitive subsystems. A mechanism by which the use of diagrammatic ERs may facilitate self-explanation is also proposed. The thesis concludes with an argument in favour of a domain-independent 'ER curriculum'. It is suggested that direct instruction in the use of a range of ERs might equip students with wider representational repertoires and hence allow them more scope to indulge their representational preferences. Finally, several directions for future work are proposed. These include extending the representational semantics of switchERII, evaluating various types of system feedback and implementing a mechanism for checking for slips during read-off from ERs.
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Tsui, Chi-Yan. "Teaching and Learning Genetics with Multiple Representations." Thesis, Curtin University, 2003. http://hdl.handle.net/20.500.11937/1614.
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This study investigated the secondary school students' learning of genetics when their teachers included an interactive computer program BioLogica in classroom teaching and learning. Genetics is difficult to teach and learn at school because it is conceptually and linguistically complex for students who have little or no prior knowledge about it. Yet genetics is now central to learning and research in biomedical sciences and is essential for understanding contemporary issues such as genetic engineering and cloning. Interactive multimedia programs such as BioLogica have provided new opportunities for learning as these programs feature multiple external representations (MERs) of knowledge in different formats, including visualgraphical and verbal-textual and at different levels of organisation. Users can manipulate and observe the behaviour of these MERs. Ainsworth (1999) summarised three functions of MERs claimed by researchers in supporting learners - to provide complementary information or processes, to constrain interpretations of phenomena and to promote construction of deeper understanding of the domain. Using an interpretive, case-based research approach with multiple methods and multiple sources of data, this study was guided by two foci of inquiry - teachers' integration and implementation of BioLogica in their classroom teaching, and students' learning with BioLogica alongside other resources. The theoretical framework drew on perspectives from educational psychology, the conceptual learning model in science education, and cognitive/computational sciences.Student learning was interpreted using a multidimensional conceptual change framework (Tyson, Venville, Harrison, & Treagust, 1997)-social/affective dimension in terms of students' interests and motivations, epistemological dimension in terms of genetics reasoning of six types (Hickey & Kindfield, 1999), and ontological dimension in terms students' gene conceptions (Venville & Treagust, 1998). Teaching and learning with BioLogica were also analysed and interpreted using Ainsworth's three functions of MERs. Necessary techniques including triangulation were used to increase the rigour of data analysis and interpretation in keeping with the qualitative research tradition. The study was conducted during the years 2001 and 2002 at six classroom sites across four senior high schools of different contexts in the metropolitan Perth area in Western Australia. Five teachers and their Year 10 students (four classes) and Year 12 students (two classes) - 117 students (90 girls and 27 boys), aged from 14 to 18, - participated in the study. Data were collected in response to the initial research questions and the reformulated case-specific research questions. The findings in terms of general assertions were generated from within-case and cross-case analyses and interpretations. Findings of the study suggest that teachers idiosyncratically incorporated (rather than integrated) BioLogica activities in their classroom teaching based on their beliefs and referents for normal classroom teaching. The teachers' implementation and scaffolding of student learning with BioLogica were affected by their knowledge of the software and beliefs about its usefulness based on the salient features of the MERs rather than their functions.Institutional support, technical issues, and time constraints were the possible barriers for using BioLogica in teaching. The findings also suggest that most students were motivated and enjoyed learning with BioLogica but not all who were actively engaged in the activities improved their genetics reasoning. Mindfulness (Salomon & Globerson, 1987) in learning with the BioLogica MERs, learning together with peers, scaffolded learning within the zone of proximal development (Vygotsky, 1978) were deemed important to students' conceptual learning. The postinstructional gene conceptions of most students were not sophisticated and were generally intelligible-plausible (IP) but not intelligible-plausible-fruitful (IPF). While most students identified two salient features of BioLogica MERs, visualisation and instant feedback, some students who substantially improved their reasoning believed that these two features helped their understanding of genetics. Overall, students exhibited social/affective (motivational) and epistemological conceptual change but little or no ontological change. The findings have implications for further and future research. First, Thorley's status analysis is useful in analysing multidimensional conceptual change (Tyson et al., 1997). Second, MERs have provided new learning opportunities and challenges for classroom learning and science teacher education. Third, there is urgency for improving Year 10 genetics teaching and learning. Fourth, the notion of multiple representations is promising in unifying theoretical constructs in psychology, cognitive/computational sciences, science education and science teacher education.
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Tsui, Chi-Yan. "Teaching and Learning Genetics with Multiple Representations." Curtin University of Technology, Science and Mathematics Education Centre, 2003. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=14027.
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This study investigated the secondary school students' learning of genetics when their teachers included an interactive computer program BioLogica in classroom teaching and learning. Genetics is difficult to teach and learn at school because it is conceptually and linguistically complex for students who have little or no prior knowledge about it. Yet genetics is now central to learning and research in biomedical sciences and is essential for understanding contemporary issues such as genetic engineering and cloning. Interactive multimedia programs such as BioLogica have provided new opportunities for learning as these programs feature multiple external representations (MERs) of knowledge in different formats, including visualgraphical and verbal-textual and at different levels of organisation. Users can manipulate and observe the behaviour of these MERs. Ainsworth (1999) summarised three functions of MERs claimed by researchers in supporting learners - to provide complementary information or processes, to constrain interpretations of phenomena and to promote construction of deeper understanding of the domain. Using an interpretive, case-based research approach with multiple methods and multiple sources of data, this study was guided by two foci of inquiry - teachers' integration and implementation of BioLogica in their classroom teaching, and students' learning with BioLogica alongside other resources. The theoretical framework drew on perspectives from educational psychology, the conceptual learning model in science education, and cognitive/computational sciences.Student learning was interpreted using a multidimensional conceptual change framework (Tyson, Venville, Harrison, & Treagust, 1997)-social/affective dimension in terms of students' interests and motivations, epistemological dimension in terms of genetics reasoning of six types (Hickey & Kindfield, 1999), and ontological dimension in terms students' gene conceptions (Venville & Treagust, 1998). Teaching and learning with BioLogica were also analysed and interpreted using Ainsworth's three functions of MERs. Necessary techniques including triangulation were used to increase the rigour of data analysis and interpretation in keeping with the qualitative research tradition. The study was conducted during the years 2001 and 2002 at six classroom sites across four senior high schools of different contexts in the metropolitan Perth area in Western Australia. Five teachers and their Year 10 students (four classes) and Year 12 students (two classes) - 117 students (90 girls and 27 boys), aged from 14 to 18, - participated in the study. Data were collected in response to the initial research questions and the reformulated case-specific research questions. The findings in terms of general assertions were generated from within-case and cross-case analyses and interpretations. Findings of the study suggest that teachers idiosyncratically incorporated (rather than integrated) BioLogica activities in their classroom teaching based on their beliefs and referents for normal classroom teaching. The teachers' implementation and scaffolding of student learning with BioLogica were affected by their knowledge of the software and beliefs about its usefulness based on the salient features of the MERs rather than their functions.
Institutional support, technical issues, and time constraints were the possible barriers for using BioLogica in teaching. The findings also suggest that most students were motivated and enjoyed learning with BioLogica but not all who were actively engaged in the activities improved their genetics reasoning. Mindfulness (Salomon & Globerson, 1987) in learning with the BioLogica MERs, learning together with peers, scaffolded learning within the zone of proximal development (Vygotsky, 1978) were deemed important to students' conceptual learning. The postinstructional gene conceptions of most students were not sophisticated and were generally intelligible-plausible (IP) but not intelligible-plausible-fruitful (IPF). While most students identified two salient features of BioLogica MERs, visualisation and instant feedback, some students who substantially improved their reasoning believed that these two features helped their understanding of genetics. Overall, students exhibited social/affective (motivational) and epistemological conceptual change but little or no ontological change. The findings have implications for further and future research. First, Thorley's status analysis is useful in analysing multidimensional conceptual change (Tyson et al., 1997). Second, MERs have provided new learning opportunities and challenges for classroom learning and science teacher education. Third, there is urgency for improving Year 10 genetics teaching and learning. Fourth, the notion of multiple representations is promising in unifying theoretical constructs in psychology, cognitive/computational sciences, science education and science teacher education.
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Talbot, Jeanne D. "Evidence for multiple cortical representations of pain in humans." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0023/NQ33090.pdf.
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Waldin, Earl DeWitt. "Using multiple representations for efficient communication of abstract values." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/12869.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1992.Includes bibliographical references (p. 217-223).
by Earl DeWitt Waldin.
Ph.D.
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Akkus, Cikla Oylum. "The Effects Of Multiple Representations-based Instruction On Seventh Grade Students'." Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605615/index.pdf.
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The purpose of this study was to investigate the effects of multiple representations-based instruction on seventh grade students’
algebra performance, attitudes toward mathematics, and representation preference compared to the conventional teaching. Moreover, it was aimed to find out how students use multiple representations in algebraic situations and the reasons of preferring certain modes of representations. The study was conducted in four seventh grade classes from two public schools in Ankara in the 2003-2004 academic year, lasting eight weeks. For assessing algebra performance, three instruments called algebra achievement test, translations among representations skill test, and Chelsea diagnostic algebra test were used. To assess students&
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attitudes towards mathematics, mathematics attitude scale, to determine students&
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representation preferences before and after the treatment representation preference inventory were administered. Furthermore, as qualitative data, interview task protocol was prepared and interviews were carried out with the students from experimental and control classes. The quantitative analyses were conducted by using multivariate covariance analyses. The results revealed that multiple representations-based instruction had a significant effect on students&
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algebra performance compared to the conventional teaching. There was no significant difference between the experimental and control groups in terms of their attitudes towards mathematics. The chi square analyses revealed that treatment made a significant contribution to the students&
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representation preferences. The results of the interviews indicated that the experimental group students used variety of representations for algebra problems and were capable of using the most appropriate one for the given algebra problems.
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Flanders, Steven Todd. "Investigating flexibility, reversibility, and multiple representations in a calculus environment." Thesis, University of Pittsburgh, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3690743.
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This study investigates the development of flexibility and reversibility in a calculus environment that attends to linking multiple representations. Reversibility was studied through Krutetskii’s framework of reversibility of two-way processes and reversibility of the mental process in reasoning. The study was conducted over approximately four months in a high school calculus classroom in an urban school district in a mid-Atlantic state. Instruction attended to linking multiple representations whenever possible. Four types of data were collected: 1) a pre-test, 2) a post-test, 3) daily assessments, and 4) clinical interviews. Twenty-one students completed a pretest and post-test that together assessed development of flexibility over the course of the study. They also completed daily assessments that were collected to provide evidence of the development of reversibility during the course of the study. Six students participated in four clinical interviews each, spread throughout the study. Inferential statistics were used to compare the results of the pre-test and post-test for significant differences and to determine significant differences in the presence of reversibility on the daily assessments over the course of the study. The clinical interviews were analyzed for evidence of students’ thought processes while solving reversible questions. Analysis revealed that over the course of the study, students demonstrated significant increases in both flexibility and reversibility. Two-way reversibility seemed to develop with relative ease for most students and often developed simultaneously with learning a forward process. Developing reversibility of the mental process in reasoning was difficult and tended to develop simultaneously with learning in a forward direction for students with high levels of flexibility. For students who did not develop reversibility simultaneously with forward learning, both two-way reversibility and reversibility of the mental process in reasoning were able to develop through multiple opportunities to solve reversible tasks of similar content. Analysis of the clinical interviews indicated that students typically followed a 4-step thought process when using reversibility to solve problems. Implications and limitations of the study and areas of further research were discussed.
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Chongburee, Wachira. "Implementation of Iterative Reconstruction of Images from Multiple Bases Representations." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/35379.
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Usually, image compression techniques that use only one transform exhibit some poor properties. For instance, the Discrete Cosine Transform (DCT) cannot efficiently represent high frequency components, resulting in blurred images. The Multiple Bases Representation (MBR) compression technique, which uses two or more transforms, is found to be superior to the single transform techniques in terms of representation efficiency. However, some bits in the MBR representation are needed to track the basis information. The MBR image quality is deteriorated by discontinuities at block boundaries, as is the standard DCT transform.
In this thesis, test images are distorted by MBR compression using a Recursive Residual Projection algorithm. This algorithm is a sub-optimal method to find the best basis vector subset for representing images based on multiple orthogonal bases. The MBR distorted images are reconstructed by the iterative method of Projection onto Convex Sets (POCS). Many constraints that form convex sets are reviewed and examined.
Due to the high distortion at the block boundaries, some constraints are introduced particularly to reduce artifacts at the boundaries. Some constraints add energy to the reconstructed images while others remove energy. Thus, the initial vectors play a key role in the performance of the POCS method for better MBR reconstruction. This thesis also determines the most appropriate initial vector for each constraint.
Finally, the composite projections associated with the sign, minimum decreasing and norm-of-slope constraints are used to improve the reconstruction of the MBR distorted images and the effect of ordering of the projections is investigated.
Master of Science
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Kanayet, Frank J. "Evidence for Multiple Representations of Number in the Human Brain." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1250463574.
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Miguel, Agnieszka C. "Image compression using overcomplete wavelet representations for multiple description coding /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/5920.
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Burkhart, Craig. "Approval Voting Theory with Multiple Levels of Approval." Scholarship @ Claremont, 2012. https://scholarship.claremont.edu/hmc_theses/26.
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Approval voting is an election method in which voters may cast votes for as many candidates as they desire. This can be modeled mathematically by associating to each voter an approval region: a set of potential candidates they approve. In this thesis we add another level of approval somewhere in between complete approval and complete disapproval. More than one level of approval may be a better model for a real-life voter's complex decision making. We provide a new definition for intersection that supports multiple levels of approval. The case of pairwise intersection is studied, and the level of agreement among voters is studied under restrictions on the relative size of each voter's preferences. We derive upper and lower bounds for the percentage of agreement based on the percentage of intersection.
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Rice, Rebekah R. "Envisioning the Mind: Children's Representations of Mental Processes." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/9654.
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Inspired by writings on creativity and by Howard Gardner's theory of multiple intelligences, I conducted a series of ten "exercises" -- each of them a guided visualization followed by an opportunity to produce -- with nine- and ten-year-old students. The visualizations, which were designed to encourage the students to explore some of the many ways our minds have of knowing and learning, began with a simple relaxation exercise and proceeded to more challenging exercises involving, for instance, kinesthetic learning, sensory awareness, the logical and linguistic mind versus the spatial mind, and intra- and interpersonal intelligence. Following each visualization the students discussed what they had experienced (transcripts of the visualizations and the discussions are included in the thesis). The students responded in visual terms as well: after each visualization, each student created a two- or three-dimensional piece of art from materials such as matboard, construction and origami paper, glue, felt-tip pens, pipe cleaners, and plastic-coated wire. These visual responses have been photographed, described, and scored according to the number of materials used, the number of colors used, and the dimensionality of the piece (photos, descriptions, and scores are included in the "Gallery". I found, surprisingly, that the visualizations in which the students were the most imaginatively engaged did not always produce the most interesting art, and that girls were much less likely than boys to create three-dimensional pieces, although girls tended to use more colors and occasionally used relief on otherwise two-dimensional pieces.Master of Architecture
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Vaughan, Rachel. "The illness representations of multiple sclerosis and their relations to outcome." Thesis, University of Leicester, 1999. http://hdl.handle.net/2381/31282.
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Illness representations were assessed in 103 adults with multiple sclerosis (MS) using a widely accepted generic five-component structure of identity, time-line, consequences, cause and cure/controllability. A cross-sectional, correlational design was employed to examine the relationships between the different components of illness representations and the length of time that people had been diagnosed with MS, which demonstrated that no significant associations existed. The inter-relationships among the five components, as well as, the associations between he different components of illness representations and outcome (i.e. illness intrusiveness, physical functioning, depression, anxiety and self-esteem) were also explored. The consequences component showed the most inter-relationships, being positively related to the identity and time-line components and negatively related with the cure/controllability dimension. The identity and consequences were significantly related with each of the areas of outcome, indicating that a strong illness identity and a belief in more serious consequences were associated with greater impairment in each outcome area. A series of stepwise multiple regression analyses were used to determine whether the illness representation components predicted outcome. Overall, illness representations, were important predictors of outcome, where the consequences component was the most important predictor of each outcome area. The perception that MS had serious consequences for the lives of individuals with MS therefore associated with higher levels of illness intrusiveness, greater impairment of physical functioning, higher levels of depression and anxiety, and lower self-esteem. These findings provide evidence to suggest that healthcare professionals who have contact with people with MS should have an awareness of the importance of illness representations and their relations to outcome for this illness population. This would therefore allow individuals with beliefs that may result in psychological, social and physical difficulties to be identified.
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Orme, Elizabeth. "Identifying the functional architecture underlying multiple representations in visual working memory." Thesis, Northumbria University, 2009. http://nrl.northumbria.ac.uk/2630/.
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This thesis aimed to investigate how visual working memory takes advantage of long-term knowledge in order to allow semantic elaboration in the form of chunking and the role of the central executive in this process. Two leading theoretical frameworks of working memory which both emphasise the role of long-term memory are discussed. One of which views working memory as consisting of multiple discrete, modality specific subsystems (Baddeley, 2000) and one which views working memory as an activated subset of long term memory (Cowan, 2005). Both of these models propose the integration of short- and long-term representations to be attentionally demanding. To investigate this assumption, two forms of visual matrix pattern were generated; a high semantic set which lends itself to long-term memory support and a low semantic set which does so to a lesser extent. The initial block of empirical work aimed to establish the characteristics of the patterns sets. Superiority for the high semantic patterns was observed in terms of greater stability across increasing maintenance intervals. The benefit of increased presentation time was also shown to be greater for the high semantic pattern set indicating the importance of time in the semantic elaboration process. A second block of studies was then conducted to identify the implications of the two patterns sets for the functional architecture of working memory. In a secondary interference paradigm the pattern sets were shown to be differentially dependent on visual and verbal interference with low semantic patterns negatively affected by visual and not verbal interference and the opposite pattern observed for high semantic patterns. The use of executive and attentional interference paradigms demonstrated two levels of binding. Firstly, when attentional resources were continually captured by a secondary task, a degree of chunking was observed for both pattern sets, this is discussed in terms of passive binding on the basis of long-term knowledge in the absence of executive resources. In the absence of interference, effortful elaboration of the pattern sets is observed and this is greater for the high semantic patterns. This is discussed in terms of active binding with the involvement of executive resources. These findings are then discussed in terms of both the Cowan (2005) and Baddeley (2000) models and recent observations made by Baddeley et al (in press) to support a modification of the episodic buffer in Baddeley's model to allow for both passive and active binding and how this leads to striking similarities between the two theoretical perspectives.
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Pellicanò, Nicola. "Tackling pedestrian detection in large scenes with multiple views and representations." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS608/document.
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La détection et le suivi de piétons sont devenus des thèmes phares en recherche en Vision Artificielle, car ils sont impliqués dans de nombreuses applications. La détection de piétons dans des foules très denses est une extension naturelle de ce domaine de recherche, et l’intérêt croissant pour ce problème est lié aux évènements de grande envergure qui sont, de nos jours, des scenarios à risque d’un point de vue de la sûreté publique. Par ailleurs, les foules très denses soulèvent des problèmes inédits pour la tâche de détection. De par le fait que les caméras ont le champ de vision le plus grand possible pour couvrir au mieux la foule les têtes sont généralement très petites et non texturées. Dans ce manuscrit nous présentons un système complet pour traiter les problèmes de détection et de suivi en présence des difficultés spécifiques à ce contexte. Ce système utilise plusieurs caméras, pour gérer les problèmes de forte occultation. Nous proposons une méthode robuste pour l’estimation de la position relative entre plusieurs caméras dans le cas des environnements requérant une surveillance. Ces environnements soulèvent des problèmes comme la grande distance entre les caméras, le fort changement de perspective, et la pénurie d’information en commun. Nous avons alors proposé d’exploiter le flot vidéo pour effectuer la calibration, avec l’objectif d’obtenir une solution globale de bonne qualité. Nous proposons aussi une méthode non supervisée pour la détection des piétons avec plusieurs caméras, qui exploite la consistance visuelle des pixels à partir des différents points de vue, ce qui nous permet d’effectuer la projection de l’ensemble des détections sur le plan du sol, et donc de passer à un suivi 3D. Dans une troisième partie, nous revenons sur la détection supervisée des piétons dans chaque caméra indépendamment en vue de l’améliorer. L’objectif est alors d’effectuer la segmentation des piétons dans la scène en partant d’une labélisation imprécise des données d’apprentissage, avec des architectures de réseaux profonds. Comme dernière contribution, nous proposons un cadre formel original pour une fusion de données efficace dans des espaces 2D. L’objectif est d’effectuer la fusion entre différents capteurs (détecteurs supervisés en chaque caméra et détecteur non supervisé en multi-vues) sur le plan du sol, qui représente notre cadre de discernement. nous avons proposé une représentation efficace des hypothèses composées qui est invariante au changement de résolution de l’espace de recherche. Avec cette représentation, nous sommes capables de définir des opérateurs de base et des règles de combinaison efficaces pour combiner les fonctions de croyance. Enfin, notre approche de fusion de données a été évaluée à la fois au niveau spatial, c’est à dire en combinant des détecteurs de nature différente, et au niveau temporel, en faisant du suivi évidentiel de piétons sur de scènes à grande échelle dans des conditions de densité variablePedestrian detection and tracking have become important fields in Computer Vision research, due to their implications for many applications, e.g. surveillance, autonomous cars, robotics. Pedestrian detection in high density crowds is a natural extension of such research body. The ability to track each pedestrian independently in a dense crowd has multiple applications: study of human social behavior under high densities; detection of anomalies; large event infrastructure planning. On the other hand, high density crowds introduce novel problems to the detection task. First, clutter and occlusion problems are taken to the extreme, so that only heads are visible, and they are not easily separable from the moving background. Second, heads are usually small (they have a diameter of typically less than ten pixels) and with little or no textures. This comes out from two independent constraints, the need of one camera to have a field of view as high as possible, and the need of anonymization, i.e. the pedestrians must be not identifiable because of privacy concerns.In this work we develop a complete framework in order to handle the pedestrian detection and tracking problems under the presence of the novel difficulties that they introduce, by using multiple cameras, in order to implicitly handle the high occlusion issues.As a first contribution, we propose a robust method for camera pose estimation in surveillance environments. We handle problems as high distances between cameras, large perspective variations, and scarcity of matching information, by exploiting an entire video stream to perform the calibration, in such a way that it exhibits fast convergence to a good solution. Moreover, we are concerned not only with a global fitness of the solution, but also with reaching low local errors.As a second contribution, we propose an unsupervised multiple camera detection method which exploits the visual consistency of pixels between multiple views in order to estimate the presence of a pedestrian. After a fully automatic metric registration of the scene, one is capable of jointly estimating the presence of a pedestrian and its height, allowing for the projection of detections on a common ground plane, and thus allowing for 3D tracking, which can be much more robust with respect to image space based tracking.In the third part, we study different methods in order to perform supervised pedestrian detection on single views. Specifically, we aim to build a dense pedestrian segmentation of the scene starting from spatially imprecise labeling of data, i.e. heads centers instead of full head contours, since their extraction is unfeasible in a dense crowd. Most notably, deep architectures for semantic segmentation are studied and adapted to the problem of small head detection in cluttered environments.As last but not least contribution, we propose a novel framework in order to perform efficient information fusion in 2D spaces. The final aim is to perform multiple sensor fusion (supervised detectors on each view, and an unsupervised detector on multiple views) at ground plane level, that is, thus, our discernment frame. Since the space complexity of such discernment frame is very large, we propose an efficient compound hypothesis representation which has been shown to be invariant to the scale of the search space. Through such representation, we are capable of defining efficient basic operators and combination rules of Belief Function Theory. Furthermore, we propose a complementary graph based description of the relationships between compound hypotheses (i.e. intersections and inclusion), in order to perform efficient algorithms for, e.g. high level decision making.Finally, we demonstrate our information fusion approach both at a spatial level, i.e. between detectors of different natures, and at a temporal level, by performing evidential tracking of pedestrians on real large scale scenes in sparse and dense conditions
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Tsogkas, Stavros. "Mid-level representations for modeling objects." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLC012/document.
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Dans cette thèse, nous proposons l'utilisation de représentations de niveau intermédiaire, et en particulier i) d'axes médians, ii) de parties d'objets, et iii) des caractéristiques convolutionnels, pour modéliser des objets.La première partie de la thèse traite de détecter les axes médians dans des images naturelles en couleur. Nous adoptons une approche d'apprentissage, en utilisant la couleur, la texture et les caractéristiques de regroupement spectral pour construire un classificateur qui produit une carte de probabilité dense pour la symétrie. Le Multiple Instance Learning (MIL) nous permet de traiter l'échelle et l'orientation comme des variables latentes pendant l'entraînement, tandis qu'une variante fondée sur les forêts aléatoires offre des gains significatifs en termes de temps de calcul.Dans la deuxième partie de la thèse, nous traitons de la modélisation des objets, utilisant des modèles de parties déformables (DPM). Nous développons une approche « coarse-to-fine » hiérarchique, qui utilise des bornes probabilistes pour diminuer le coût de calcul dans les modèles à grand nombre de composants basés sur HOGs. Ces bornes probabilistes, calculés de manière efficace, nous permettent d'écarter rapidement de grandes parties de l'image, et d'évaluer précisément les filtres convolutionnels seulement à des endroits prometteurs. Notre approche permet d'obtenir une accélération de 4-5 fois sur l'approche naïve, avec une perte minimale en performance.Nous employons aussi des réseaux de neurones convolutionnels (CNN) pour améliorer la détection d'objets. Nous utilisons une architecture CNN communément utilisée pour extraire les réponses de la dernière couche de convolution. Nous intégrons ces réponses dans l'architecture DPM classique, remplaçant les descripteurs HOG fabriqués à la main, et nous observons une augmentation significative de la performance de détection (~14.5% de mAP).Dans la dernière partie de la thèse nous expérimentons avec des réseaux de neurones entièrement convolutionnels pous la segmentation de parties d'objets.Nous réadaptons un CNN utilisé à l'état de l'art pour effectuer une segmentation sémantique fine de parties d'objets et nous utilisons un CRF entièrement connecté comme étape de post-traitement pour obtenir des bords fins.Nous introduirons aussi un à priori sur les formes à l'aide d'une Restricted Boltzmann Machine (RBM), à partir des segmentations de vérité terrain.Enfin, nous concevons une nouvelle architecture entièrement convolutionnel, et l'entraînons sur des données d'image à résonance magnétique du cerveau, afin de segmenter les différentes parties du cerveau humain.Notre approche permet d'atteindre des résultats à l'état de l'art sur les deux types de donnéesIn this thesis we propose the use of mid-level representations, and in particular i) medial axes, ii) object parts, and iii)convolutional features, for modelling objects.The first part of the thesis deals with detecting medial axes in natural RGB images. We adopt a learning approach, utilizing colour, texture and spectral clustering features, to build a classifier that produces a dense probability map for symmetry. Multiple Instance Learning (MIL) allows us to treat scale and orientation as latent variables during training, while a variation based on random forests offers significant gains in terms of running time.In the second part of the thesis we focus on object part modeling using both hand-crafted and learned feature representations. We develop a coarse-to-fine, hierarchical approach that uses probabilistic bounds for part scores to decrease the computational cost of mixture models with a large number of HOG-based templates. These efficiently computed probabilistic bounds allow us to quickly discard large parts of the image, and evaluate the exact convolution scores only at promising locations. Our approach achieves a $4times-5times$ speedup over the naive approach with minimal loss in performance.We also employ convolutional features to improve object detection. We use a popular CNN architecture to extract responses from an intermediate convolutional layer. We integrate these responses in the classic DPM pipeline, replacing hand-crafted HOG features, and observe a significant boost in detection performance (~14.5% increase in mAP).In the last part of the thesis we experiment with fully convolutional neural networks for the segmentation of object parts.We re-purpose a state-of-the-art CNN to perform fine-grained semantic segmentation of object parts and use a fully-connected CRF as a post-processing step to obtain sharp boundaries.We also inject prior shape information in our model through a Restricted Boltzmann Machine, trained on ground-truth segmentations.Finally, we train a new fully-convolutional architecture from a random initialization, to segment different parts of the human brain in magnetic resonance image data.Our methods achieve state-of-the-art results on both types of data
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Ollion, Charles. "Emergence of internal representations in evolutionary robotics : influence of multiple selective pressures." Phd thesis, Université René Descartes - Paris V, 2013. http://tel.archives-ouvertes.fr/tel-00948029.
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Luxford, Cynthia Joan. "Use of Multiple Representations to Explore Students’ Understandings of Covalent and Ionic Bonding as Measured by the Bonding Representations Inventory." Miami University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=miami1366031143.
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Ott, Natalie [Verfasser], and Roland [Akademischer Betreuer] Brünken. "From dual coding to multiple coding : Effects of multiple symbolic representations for mathematical understanding / Natalie Ott ; Betreuer: Roland Brünken." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2017. http://d-nb.info/1152094300/34.
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Ott, Natalie Verfasser], and Roland [Akademischer Betreuer] [Brünken. "From dual coding to multiple coding : Effects of multiple symbolic representations for mathematical understanding / Natalie Ott ; Betreuer: Roland Brünken." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:291-scidok-ds-268806.
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Özgün-Koca, S. Asli. "Computer-based representations in mathematics classrooms : the effects of multiple linked and semi-linked representations on students' learning of linear relationships /." The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486399451962818.
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Brey, Amina. "Multiple representations and cognitive load: words, arrows, and colours when solving algebraic problems." Thesis, Nelson Mandela Metropolitan University, 2013. http://hdl.handle.net/10948/d1020392.
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This study investigates the possible effects that access to selected multiple representations (words, arrows and colours) have in terms of cognitive load and learner achievement when presented with algebraic problems at grade nine level. The presentation of multiple representations (the intervention) was intended to decrease extraneous cognitive load, manage the intrinsic cognitive load (algebraic problems) and optimise germane cognition (schema acquisition and automation). An explanatory sequential mixed-method design was employed with six hundred and seventy three learners in four secondary schools. Quantitative data were generated via pre-, intervention and post-tests/questionnaires, while qualitative data were obtained from open-ended questions in the pre-, intervention, and post-tests/questionnaires, eight learner focus group interviews (n = 32), and four semi-structured, open-ended teacher interviews. Statistically and practically significant improvement in mean test scores from the pre- to intervention test scores in all schools was noted. No statistically and practically significant improvement was noted in further post-tests except for post-test 2 which employed more challenging problems (statistically significant decrease with a small practical effect). Learners expressed their preference for arrows, followed by colours and then words as effective representations. Teacher generated qualitative data suggests that they realise the importance of using multiple representations as an instructional strategy and implicitly understand the notion of cognitive load. The findings, when considered in the light of literature on cognitive load, suggest that a reduction in extraneous cognitive load by using a more effective instructional design (multiple representations) frees working memory capacity which can then be devoted to the intrinsic cognitive load (algebraic problems) and thereby increase germane cognition (schema acquisition and automation).
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Magadla, Anadin Zakhele. "Teaching Ohm's law in Grade 11 Physical Sciences using a Multiple Representations Approach." University of the Western Cape, 2018. http://hdl.handle.net/11394/5928.
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Magister Educationis - MEd (Mathematics and Science Education)The purpose of this study was to investigate the value of teaching Ohm's law in Grade 11 using a Multiple Representations Approach (MRA). The need to promote knowledge and skills in problem solving in Physical Sciences together with the use of technology is important. This study explored techniques of improving learner attainment thus ensuring that they achieve the minimum entry requirements for science related fields at university. Methodology A case study approach was used. The context is a rural high school in the Eastern Cape. The theoretical framework is constructivism and pedagogical content knowledge. It was a mixed method study with a sample of 48 Grade 11 Physical Sciences learners. Data was collected through a pre-test, an intervention and a post-test. The intervention lessons on Ohm's law were video-taped. A control group was taught using traditional teaching methods and the experimental group was taught using the Multiple Representations Approach. Post-test scores compared the achievement in the two groups. It was followed by focus group interviews with the learners in the two groups. Findings The study found that MRA improved learner attainment and assisted in overcoming learning difficulties. It assessed and developed a variety of learners' skills in different forms at different stages of the lesson. The study found that the MRA aroused learners' interest in science and assisted them to visualise the abstract concepts and this led to an understanding of difficult concepts. Recommendations The study recommends the use of MRA's by science teachers to increase learners' understanding of Ohm's law. It is recommended that teachers develop fun and interesting science activities to encourage the love of science among learners.
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Sharma, A. "Reconstructing the geometry of a 3-dimensional model using multiple visible surface representations." Thesis, De Montfort University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233862.
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Bridson, David J. "The influence of multiple representations on the learning of calculus by ESL students." Thesis, Curtin University, 2002. http://hdl.handle.net/20.500.11937/2624.
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The goals of this study were to research the learning difficulties among a group of four pre-university introductory calculus students who were mainly international students studying English as a Second Language (M). The intention was to create a constructivist-style classroom environment in order to determine if it could improve students` knowledge about the use and management of multiple representations (that is, graphical, rum~ symbolic, pictorial, linguistic or diagrammatic approaches for problem representation), increase their classroom communication as a means to improving ability in the modelling of calculus word problems, and to develop, implement and evaluate a teaching package that encouraged the use of multiple representations as a means of improving conceptual understanding. The achievement of these goals was sought by means of the development, implementation and evaluation of a number of calculus extended tasks that encouraged the use of multiple representations. These activities facilitated the compilation of a menu of approaches to the solution of mathematical problems, while the longitudinal nature of the study allowed for the monitoring of student changes in their preferred approach. A traditional calculus curriculum was used for the study, but the instructional emphasis was based more on students' understanding of concepts in a classroom environment utilising a constructivist approach rather than on their memorising computational techniques. Reading, writing, and discussion were emphasised m small group settings to develop language skills and to foster an appreciation of the alternative solution strategies of individual students.The study was conducted at an International College north of Perth in Western Australia, and the majority of students in the sample were from Non-English-Speaking-Backgrounds (NESB). A range of methods was used to collect qualitative and quantitative data in order to increase the credibility of the research. These methods included audio recordings of structured task-based interviews with each of the four students in the sample; teacher analysis of student worksheets; my classroom observations; the analysis of alternative student conceptions on assessment tasks obtained through post-test interviews, and my personal reflections. Quality controls were employed to ensure the credibility of the data collected. As classroom teacher and principal researcher, it was possible for me to treat each of the four students involved as an individual case study. Descriptive questionnaires were used in order to gain information regarding the course and the use of graphics calculators. The results are applicable to ESL introductory calculus students only, and the nature of the sample implies a number of study limitations detailed in Chapter Five. There was extensive evidence of the benefits of the use of a multi-representational mode and evidence also of the benefits of encouraging the use of a diversity of modes of classroom instruction. Outcomes of the study were qualified by the difficulties ESL students face in coordinating conflicting information and interpreting the language demands of problem presentation. It is expected that this study will assist m extending the knowledge and understanding of the learning difficulties faced by ESL students in the am of pre-university calculus.Results of this study suggest that instructional material has an important influence on ESL students’ use and management of multiple representations. However, there are often limitations to the influence of the material due to student preferences, mathematical ability and firmly held beliefs as well as on the amount of detail presented in a problem Secondly, small group learning environments based on a constructivist approach were found to influence student ability to model calculus word problems in a positive manner, provided there is teacher support to overcome cognitive obstacles. Finally, it was established that an effective teaching package could be developed to assist ESL students in calculus learning. The teaching package's evaluation highlighted the need for matching language use in problem presentation with the current mathematical language register of each student.
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Bridson, David J. "The influence of multiple representations on the learning of calculus by ESL students." Curtin University of Technology, Science and Mathematics Education Centre, 2002. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=13544.
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The goals of this study were to research the learning difficulties among a group of four pre-university introductory calculus students who were mainly international students studying English as a Second Language (M). The intention was to create a constructivist-style classroom environment in order to determine if it could improve students` knowledge about the use and management of multiple representations (that is, graphical, rum~ symbolic, pictorial, linguistic or diagrammatic approaches for problem representation), increase their classroom communication as a means to improving ability in the modelling of calculus word problems, and to develop, implement and evaluate a teaching package that encouraged the use of multiple representations as a means of improving conceptual understanding. The achievement of these goals was sought by means of the development, implementation and evaluation of a number of calculus extended tasks that encouraged the use of multiple representations. These activities facilitated the compilation of a menu of approaches to the solution of mathematical problems, while the longitudinal nature of the study allowed for the monitoring of student changes in their preferred approach. A traditional calculus curriculum was used for the study, but the instructional emphasis was based more on students' understanding of concepts in a classroom environment utilising a constructivist approach rather than on their memorising computational techniques. Reading, writing, and discussion were emphasised m small group settings to develop language skills and to foster an appreciation of the alternative solution strategies of individual students.The study was conducted at an International College north of Perth in Western Australia, and the majority of students in the sample were from Non-English-Speaking-Backgrounds (NESB). A range of methods was used to collect qualitative and quantitative data in order to increase the credibility of the research. These methods included audio recordings of structured task-based interviews with each of the four students in the sample; teacher analysis of student worksheets; my classroom observations; the analysis of alternative student conceptions on assessment tasks obtained through post-test interviews, and my personal reflections. Quality controls were employed to ensure the credibility of the data collected. As classroom teacher and principal researcher, it was possible for me to treat each of the four students involved as an individual case study. Descriptive questionnaires were used in order to gain information regarding the course and the use of graphics calculators. The results are applicable to ESL introductory calculus students only, and the nature of the sample implies a number of study limitations detailed in Chapter Five. There was extensive evidence of the benefits of the use of a multi-representational mode and evidence also of the benefits of encouraging the use of a diversity of modes of classroom instruction. Outcomes of the study were qualified by the difficulties ESL students face in coordinating conflicting information and interpreting the language demands of problem presentation. It is expected that this study will assist m extending the knowledge and understanding of the learning difficulties faced by ESL students in the am of pre-university calculus.
Results of this study suggest that instructional material has an important influence on ESL students’ use and management of multiple representations. However, there are often limitations to the influence of the material due to student preferences, mathematical ability and firmly held beliefs as well as on the amount of detail presented in a problem Secondly, small group learning environments based on a constructivist approach were found to influence student ability to model calculus word problems in a positive manner, provided there is teacher support to overcome cognitive obstacles. Finally, it was established that an effective teaching package could be developed to assist ESL students in calculus learning. The teaching package's evaluation highlighted the need for matching language use in problem presentation with the current mathematical language register of each student.
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Gullström, Cecilia. "Pictionary Physics: En kvalitativ undersökning av ett didaktiskt verktyg i enlighet med The Scholarship of Teaching and Learning." Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-212721.
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Den här undersökningen inom fysikdidaktik utförs enligt ramverket The Scholarship of Teaching and Learning (SoTL). Det didaktiska verktyget som ska utvärderas benämns Pictionary Physics. Studien börjar med en litteraturöversikt av multipla representationer och interaktivt engagemang. Översikten syftar till att utforska hur lärandet kan möjliggöras vid användningen av det didaktiska verktyget. Pictionary Physics användes sedan för att främja en interaktiv användning av multipla representationer i en grupp bestående av fyra studenter. Studenternas agerande studerades och analyserades kvalitativt, följt av en utvärdering av studenternas upplevelser när de använde det didaktiska verktyget. Utvärderingen visar att Pictionary Physics kan gynna konceptuell förståelse för begrepp inom fysik. Utvärderingen visar även att det didaktiska verktyget skulle kunna bidra till förbättrat studieresultat då studenter uppmuntras att använda multipla representationer på ett interaktivt sätt. Fortsatt förädling av Pictionary Physics föreslås. Detta är stommen för SoTL, där tanken är att konsekvent utöka var kunskap om lärandet av fysik.This physics education research project is carried out following the framework of the Scholarship of Teaching and Learning (SoTL). The didactic instrument investigated is termed Pictionary Physics. The study begins with a literature review of research on multiple representation, and interactive engagement. This review is used to evaluate the learning potential of the intended didactic instrument. Pictionary Physics was then used to facilitate the multi-representational interaction of a group of four physics students. The students’ behavior was studied and analyzed qualitatively, followed by an evaluation of the students’ experiences when using this didactic instrument. The investigation shows that Pictionary Physics may promote conceptual understanding of physics phenomena. The investigation also implies that this didactic instrument can contribute to improved learning outcomes when students are encouraged to interact by using multiple representations. Continued refinement of the Pictionary Physics concept is suggested. Such refinement is the essence of SoTL, incrementally expanding our knowledge of the teaching and learning of physics.
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Ngwane, Maxhoba. "Examining the use of multiple representations to teach vectors in Grade 10 physical sciences." University of the Western Cape, 2019. http://hdl.handle.net/11394/7042.
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Magister Educationis - MEdThe purpose of this paper was to examine the use of the multiple representation approach as a teaching strategy to improve learners understanding of vectors in Grade 10 Physical Sciences. The study also wanted to consider the MR approach through the lens of the learners. A sample consisting of 45 Grade 10 learners from a total of 160 Grade 10 Physical Sciences learners participated in the study. Both quantitative and qualitative data were collected and analysed. Learners were first given a pre-test to establish their initial understanding of vectors. This pre-test was followed by an intervention in the form of a lesson. The lesson was conducted in order to expose learners to learning through Multiple Representations. A post-test was then administered to determine the impact of the intervention. To gather and quantify the learners’ perceptions on the use of Multiple Representations in teaching and learning of vectors in Grade 10 Physical Sciences learners were given questionnaires to complete. The last step was interviewing of learners to triangulate the results from the three instruments. The study found that learners were struggling with understanding of vectors in their traditional chalk-and-talk lessons and their perceptions towards vectors were negative. The study also found that Multiple Representations can improve understanding and develop positive perception of learners towards the teaching and learning of vectors. This improvement occurs only if Multiple Representations is used correctly. The study further found out that when Multiple Representations is used improperly it limits deeper understanding by learners. A number of recommendations were made out of the findings of the study. Some of them were that multiple representations should be used when teaching vectors and that subject advisers and teachers should be developed on the proper use of multiple representations. The Physical Sciences textbooks must be designed to accommodate Multiple Representations.
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Cichocki, Radoslaw. "Classification of objects in images based on various object representations." Thesis, Blekinge Tekniska Högskola, Avdelningen för programvarusystem, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-5774.
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Object recognition is a hugely researched domain that employs methods derived from mathematics, physics and biology. This thesis combines the approaches for object classification that base on two features – color and shape. Color is represented by color histograms and shape by skeletal graphs. Four hybrids are proposed which combine those approaches in different manners and the hybrids are then tested to find out which of them gives best results.Mail the author at radoslaw.cichocki(at)gmail.com
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Olsson, Anna-Carin. "Factors Shaping Process and Representation in Multiple-Cue Judgment." Doctoral thesis, Umeå : Dept. of psychology, Univ, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-264.
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Adadan, Emine. "Promoting high school students' conceptual understandings of the particulate nature of matter through multiple representations." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1164178952.
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Olaleye, Bolanle Omotoke. "Enhancing teachers' knowledge for using multiple representations in teaching chemistry in Nigerian senior secondary schools." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2012. https://ro.ecu.edu.au/theses/494.
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The quality of the teaching and learning of chemistry in Nigeria is of great concern to parents, teachers, and students and has been tied to various factors such as a lack of teaching resources, learning materials and well qualified teachers, large class sizes and poor funding. This resulted in poor student performance and lack of interest in chemistry. Also, learning chemistry concepts tends to be by rote and memorising of content, and as such, students do not perceive learning chemistry as relevant to their lives. These issues motivated the Researcher to explore how teaching and learning of chemistry could be reformed in low resource Nigerian secondary schools. This study focussed on enhancing teachers‘ pedagogical knowledge and beliefs about using multiple representations in chemistry education through a professional learning program. Participating teachers attended a series of professional learning workshops on how to construct, interpret and use multiple representations to teach chemistry concepts in ways that more actively engage students in learning. The study employed a mixed method approach that included descriptive and interpretive methods. Forty senior secondary chemistry teachers completed a questionnaire to gather background data about difficulties of teaching chemistry effectively and their existing teaching practice and beliefs. Fifteen of these teachers then participated in three days of professional learning workshops and three of the participating teachers at the workshop were the subjects of a case study to evaluate the impact of the professional learning on their practice and beliefs. Students also completed a questionnaire about their experiences of learning chemistry and some students in case study classes participated in focus group discussions The research involved both qualitative and quantitative methods. The qualitative data were sourced from teacher interviews, student focus group discussions and direct classroom observation. Quantitative data, on the other hand, were collected through questionnaires administered to both participating teachers and students. The mixed data sources were triangulated to ensure confirmability of findings The study enhanced the teaching of the rate of reactions and collision theory, and water pollution and solubility concepts by using various student constructed representations such as concept maps, particulate representations, graphs, role-plays, flowcharts, and 3D physical models. The professional development intervention impacted on the teachers‘ beliefs about the nature of effective teaching and learning of chemistry. The study also enriched teachers‘ pedagogical content knowledge for actively engaging students in constructing their own representations. As an outcome from the project, a professional learning module has been developed that can be used to enhance the teaching and learning of chemistry in low resource Nigerian schools. In addition, new knowledge has been produced in relation to the to the use of multiple representations for effective chemistry teaching and learning in schools with limited resources.
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Feeney, James. "Physical disability and psychological distress in multiple sclerosis : the role of illness representations and experiential avoidance." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/37184/.
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Objectives: This study explores factors associated with psychological wellbeing and distress in people with Multiple Sclerosis (MS). The role of physical symptoms, illness representations and experiential avoidance in predicting psychological distress was assessed. Design: Cross-sectional data was collected from 121 participants with a diagnosis of MS. Path analysis was used to test a hypothetical model of distress in MS that hypothesised that experiential avoidance would mediate the relationships between level of symptoms and distress, and between illness representations and distress. Methods: Participants completed questionnaires assessing level of physical symptoms (EDSS), illness representations (BIPQ), experiential avoidance (AAQ-II), and psychological distress (GHQ-30). Path coefficients, allowing direct and indirect relationships to be evaluated, were obtained from a series of simultaneous multiple regression analyses; one for each endogenous variable (experiential avoidance, distress). Results: Participants results highlighted significant positive associations between all the variables (symptoms, illness representations, experiential avoidance) and distress. Path analysis revealed that experiential avoidance did not mediate the relationships between level of symptoms and distress, nor illness representations and distress. Illness representations were the strongest predictor of psychological distress, while experiential avoidance was the strongest predictor when distress was conceptualised as depression. Conclusions: Overall the study did not suggest that experiential avoidance mediates the relationship between illness representations and psychological distress; instead illness representations alone accounted for most of the variance in psychological distress. Experiential avoidance accounted for most of the depression experienced by participants. These results have a direct impact on how psychological interventions are delivered for people with MS, suggesting that disease factors, and beliefs about the illness, need to be taken account of and incorporated into treatment for presenting problems.
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Nemati, Mohammadreza. "Machine Learning Approaches in Kidney Transplantation Survival Analysis using Multiple Feature Representations of Donor and Recipient." University of Toledo / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1596756241492039.
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Rau, Martina A. "Conceptual learning with multiple graphical representations: Intelligent tutoring systems support for sense-making and fluency-building processes." Research Showcase @ CMU, 2013. http://repository.cmu.edu/dissertations/262.
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Most learning environments in the STEM disciplines use multiple graphical representations along with textual descriptions and symbolic representations. Multiple graphical representations are powerful learning tools because they can emphasize complementary aspects of complex learning contents. However, to benefit from multiple graphical representations, students need to engage in a number of learning processes. Educational technologies offer novel opportunities to support these learning processes by making graphical representations interactive and by providing individualized instructional support for students’ interactions with them. Yet, these opportunities are under-researched, as most prior research has taken a symbol-systems approach by focusing only on multiple representations that use different symbol systems, such as text and one additional graphical representation.
To address the open question of how to enhance students’ benefit from multiple graphical representations that use the same symbol system, I conducted a series of five classroom experiments and lab studies with over 3,000 students in grades 4-6. Each experiment tested the effectiveness of different types of instructional support for students’ learning with multiple graphical representations. Experiment 1 compares the effects of multiple over a single graphical representation and the effects of prompting students to self-explain the relation between graphical and symbolic representations. Results show that multiple graphical representations lead to better learning than a single graphical representation, provided that students receive self-explanation prompts. Experiment 2 contrasts sequences of task types and graphical representations. The results show that interleaving task types while blocking graphical representations promotes students’ learning from multiple graphical representations more so than interleaving graphical re-presentations while blocking task types. Building on Experiment 2, Experiment 3 investigates whether (in addition to moderately interleaving task types) graphical representations should also be presented in an interleaved, rather than in a blocked fashion. An analysis of learning outcomes and tutor log data demonstrates that interleaving graphical representations (while moderately interleaving task types) enhances students’ benefits from multiple graphical representations. Furthermore, Experiment 3 replicates the finding from Experiment 1 that multiple graphical representations lead to better learning than a single one. Experiment 4 investigates the effects of different types of instructional support for connection making between multiple graphical representations. The results show that a combination of support designed to help students actively make sense of the connections and of support designed to help students become fluent in making these connections is needed for students to benefit from multiple graphical representations, compared to a single graphical representation. Finally, Experiment 5 investigates different sequences of connectional sense-making support and connectional fluency-building support. The results lead to the conclusion that receiving support for making sense of connections first is a prerequisite to students’ benefit from subsequent connectional fluency-building support.
A further contribution of my thesis work is the development of an intelligent tutoring system for fractions that leads to significant and robust gains in students’ conceptual and procedural knowledge of fractions. In addition to investigating how best to support students’ learning with multiple graphical representations, each experiment also served to iteratively improve the Fractions Tutor while employing user-centered techniques. To develop the Fractions Tutor, I made use of a novel methodology to resolve stakeholder conflicts that inevitably arise in complex educational settings.
I consolidate my empirical findings in a novel theoretical framework that describes the learning processes that students perform when learning with multiple graphical representations. This framework extends existing theoretical frameworks, which have solely focused on learning with representations that use different symbol systems (such as text accompanied with one additional graphical representation), rather than on learning with multiple representations using the same symbol system (such as multiple graphical representations). My theoretical framework proposes that in order to benefit from multiple graphical representations, students need to conceptually understand each individual graphical representation and to use each graphical representation fluently to solve domain-specific problems, students need to conceptually understand the connections between different graphical representations, and they need to become fluent in making these connections.
In sum, my thesis work contributes (1) an empirically validated set of instructional design principles for the effective use of multiple graphical representations, (2) a theoretical framework for learning with multiple graphical representations that use the same symbol system, (3) an effective tutoring system for fractions learning, and (4) a new methodology for resolving design conflicts that often occur in real educational settings.
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McPadden, Daryl. "Examining Students' Representation Choices in University Modeling Instruction." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3658.
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Representations (such as pictures, diagrams, word descriptions, equations, etc.) are critical tools for learning, problem solving, and communicating in science, particularly in physics where multiple representations often serve as intermediate steps, a means to evaluate a solution, and highlight different aspects a physical phenomenon. This dissertation explores the representation choices made by students in the University Modeling Instruction (MI) courses on problems from across introductory physics content. Modeling Instruction is a two-semester introductory, calculus-based physics sequence that was designed to guide students through the process of building, testing, applying, and refining models. As a part of this modeling cycle, students have explicit instruction and practice in building, evaluating, and coordinating representations in introductory physics. Since I am particularly interested in representations across all of introductory physics, this work was situated in the second semester of MI. To address students' representation choices, the Problem Solving and Representation Use Survey (PSRUS) was developed as modified card sort survey, which asked students to simply list the representations that they would use on 25 physics questions from across introductory physics. Using non-parametric statistical tests (Mann-Whitney-Wilcox, Wilcoxon-Ranked Sign, and Cliff's Delta), I compare the number and variety of representations that students choose. Initially, students who took the first semester of MI use significantly more representations in their problem solving when compared to those who did not; however, there are significant gains in the number of representations that these students choose over the semester across the introductory physics content. After significant changes to the second semester MI curriculum, the difference between these two groups disappears, with both groups increasing their representation choices when compared to the previous semester. Using network analysis to compare students' concurrent representation choices, I also show that students use a consistent set of representations on mechanics problems; whereas, they choose a wider variety on electricity and magnetism (EM) problems. In both mechanics and EM, pictures serve as an important connecting representation between the others. I use these results to make suggestions for instructors, curriculum developers, and physics education researchers.
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Smart, Angela. "Undergraduate Students’ Connections Between the Embodied, Symbolic, and Formal Mathematical Worlds of Limits and Derivatives: A Qualitative Study Using Tall’s Three Worlds of Mathematics." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/24247.
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Calculus at the university level is taken by thousands of undergraduate students each year. However, a significant number of students struggle with the subject, resulting in poor problem solving, low achievement, and high failure rates in the calculus courses overall (e.g., Kaput, 1994; Szydlik, 2000; Tall, 1985; Tall & Ramos, 2004; White & Mitchelmore, 1996). This is cause for concern as the lack of success in university calculus creates further barriers for students who require the course for their programs of study. This study examines this issue from the perspective of Tall’s Three Worlds of Mathematics (Tall, 2004a, 2004b, 2008), a theory of mathematics and mathematical cognitive development. A fundamental argument of Tall’s theory suggests that connecting between the different mathematical worlds, named the Embodied-Conceptual, Symbolic-Proceptual, and Formal-Axiomatic worlds, is essential for full cognitive development and understanding of mathematical concepts. Working from this perspective, this research examined, through the use of calculus task questions and semi-structured interviews, how fifteen undergraduate calculus students made connections between the different mathematical worlds for the calculus topics of limits and derivatives. The analysis of the findings suggests that how the students make connections can be described by eight different Response Categories. The study also found that how the participants made connections between mathematical worlds might be influenced by the type of questions that are asked and their experience in calculus courses. I infer that these Response Categories have significance for this study and offer potential for further study and educational practice. I conclude by identifying areas of further research in regards to calculus achievement, the Response Categories, and other findings such as a more detailed study of the influence of experience.
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DeJongh, Matthew. "Causal processes in the Problem Space Computational Model : integrating multiple representations of causal processes in abductive problem solving /." The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487687959968505.
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Kuo, Yen-Ruey. "The influence of multiple representations and attitudes to learning on the first year non-physics majors' conceptual understanding." Thesis, Curtin University, 2012. http://hdl.handle.net/20.500.11937/1071.
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The study described in this thesis was conducted in a university in Australia with non-Physics majors studying Introductory Physics over three semesters. The main theme in this thesis was to study the relationship between students’ use of multiple representations, their attitudes towards learning Physics and their conceptual understanding. The assessment in the Physics unit was designed to encourage students to represent their knowledge with as many representations as they could. Two multiple representational questionnaires on the topics of thermal physics and optics were developed to assess students’ conceptual understanding and for their learning. In addition, three attitude-related surveys - Physics Motivation Survey, Expectation Survey and Experience Survey - were administered to measure students’ attitude towards learning Physics.Phase One of the study focused on observing the lecturer and tutors’ representations in class and accordingly, developing the multiple representations questionnaire prior to its first trial. In Phase Two, the revised multiple representations questionnaires were administered as the second trial, and a marking key was developed for the questionnaires. In addition, three attitude-related surveys were administered in the first trial to clarify students’ attitudes to learning, because some inattentive learning behaviours were observed in Phase One.Phase Three was the most productive phase because this phase built on what was learned from Phases One and Two. Based on the results of Phase Two, the multiple representational questionnaires testing thermal physics and optics were revised and administered in a third trial, and the three attitude related surveys were given the second trial. In addition, in Phase Three, the time spent on different representations used by the lecturer was recorded. These data were used to obtain further understanding of the relationship between multiple representations, students’ attitudes to learning Physics and students’ conceptual understanding. Also approximately 50 % of the student cohort (n = 70) was interviewed.In Phase Three, the results of post-tests of the multiple representational questionnaires showed that students’ marks varied considerably on the zero to three scale; however, the average mark of all representations, number of different mode representations presented in each question improved significantly based on both on t-tests and effect size compared to their pre-tests. It was speculated that the improvement was due to the effect of the lectures and tutorials that were designed to make students explicitly more aware of the different ways they can represent their knowledge. Besides, it was found that the time of teaching in one representation had no significant correlation with students’ improvement of mark in that representation.During the interviews, students were able to provide more elaborate and richer explanations than on their written responses alone because they were able to clarify their written responses. Students had more opportunities to confront cognitive conflicts when the interviewer reminded students about the mistakes they made in the questionnaire or in their oral explanation. The research showed that students’ prior knowledge (e.g., representational, referent and conceptual knowledge) was important to make the best use of multiple representations.The three attitude-related surveys had high Cronbach alpha reliabilities and were generally effective in measuring students’ attitudes and unit learning experiences. Based on students’ responses to the three surveys, their attitudes towards learning Physics was positive in spite of some assessment anxiety, and they reported positive experiences during the semester. Students’ expectations of the unit they attended had medium correlation(r=0.37 in thermal module, r=0.38 in optics module) with their conceptual understanding. However, the careless attitudes observed by some students may have limited their learning with multiple representations. We recommend further study examining the causes of students’ learning attitude and learning behaviour, and how these causes interact with each other to influence students’ conceptual understanding while learning physics with multiple representations.
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Zagallo, Patricia, and Patricia Zagallo. "Investigating How Undergraduate Students Develop Scientific Reasoning Skills When Coordinating Data and Model Representations in Biology." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/625586.
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There has been a call to reform science education to integrate scientific thinking practices, such as data interpretation and modeling, with learning content in science classrooms. This call to reform has taken place in both K-12 science education through Next Generation Science Standards and undergraduate education through AAAS initiative Vision and Change in Undergraduate Biology Education. This dissertation work examines undergraduate students' learning of multiple scientific thinking skills in a curricular format called Teaching Real data Interpretation with Models (TRIM) applied to a large-enrollment course in Cellular and Developmental Biology. In TRIM, students are provided worksheets in groups and tasked to interpret authentic biological data. Importantly, groups are tasked to relate their data interpretations to a 2D visual model representation of the relevant biological process. This dissertation work consists of two studies with the overarching question: How do students use model representations to interpret data interpretations? In the first study, we primarily describe how students learn to navigate and interpret discipline-based data representations. We found the majority of groups could construct quality written data interpretations. Qualitative coding analysis on group discourse found students relied on strategies such as decoding the data representation and noticing data patterns together to construct claims. Claims were refined through spontaneous collaborative argumentation. We also found groups used the provided model to connect their data inferences to a biological context. In the second study, we primarily target our analysis on how individual students relate their data interpretations to different modeling tasks, including student-generation of their own model drawing. I interviewed students one-on-one as they worked through TRIM-style worksheets. From iterative qualitative analysis of transcripts and collected video on hand movements, I characterize the forms of reasoning at play at the interface of data and model representations. I propose a model at the end of Study 2 describing three modes of reasoning in data abstraction into models. I found when relating between data and models, students needed to link signs in both representations to a common referent in the real-world phenomenon. Establishing this sign-referent relationship seemed to depend on bringing in outside mechanistic information about the phenomenon. Once a mechanism was established, students could fluidly move between data and model representations through mechanistic reasoning. Thus data abstraction seems to rely on mechanistic reasoning with models. The findings from this dissertation work support the feasibility of student development of multiple scientific thinking skills within a large lecture course, and provide targets for curriculum and assignment designs centered on teaching higher order reasoning skills.
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Linenberger, Kimberly J. "Biochemistry Students' Understandings of Enzyme-Substrate Interactions as Investigated through Multiple Representations and the Enzyme-Substrate Interactions Concept Inventory." Miami University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=miami1321309534.
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Porzio, Donald Timmis. "The effects of differing technological approaches to calculus on students' use and understanding of multiple representations when solving problems /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487858106115186.
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Zou, Xueli. "The use of multiple representations and visualizations in student learning of introductory physics : an example from work and energy /." The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488203158826859.
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Roberts, Geoff. "Classification of non-stationary signals using time-frequency representations and multiple hypotheses tests : an application to humpback whale songs." Thesis, Queensland University of Technology, 1999.
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山本, 有作, and Yusaku Yamamoto. "密行列固有値解法の最近の発展(I) : Multiple Relatively Robust Representationsアルゴリズム." 日本応用数理学会, 2005. http://hdl.handle.net/2237/10838.
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Simasiku, Bosman Muyubano. "Student teachers' experiences in using multiple representations in the teaching of grade 6 proportion word problems : a Namibian case study." Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1001703.
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This study investigated the experiences of four participating student teachers in using multiple representative approaches in the teaching of Grade 6 proportion word problems. The multiple representative approaches include the Between Comparison Method, the Within Comparison Method, the Diagrammatic Method, the Table Method, the Graph Method, the Cross-product Method, and the Oral Informal Method. An intervention programme was organised, using workshops where student teachers were prepared to teach Grade 6 proportion word problems using multiple representative approaches. The teaching practice lessons of the four participating student teachers in two primary schools were video recorded, and the focus group interview was conducted at the University Campus. With the exception of the Graph Method and the Cross-product Method, it was revealed that the multiple representative approaches were generally effective in the teaching of Grade 6 proportion word problems. The study further revealed that multiplicative relationships can be explored through using the different individual representative approaches. The study argues that the cross-product method is not the only way to teach Grade 6 proportion word problems. There are multiple representative approaches that should be used in conjunction with each other to enhance the teaching of proportion word problems. Furthermore, this study revealed that a number of challenges were encountered when using multiple representative approaches. The challenges include difficulties with the English language, different and unique abilities of the learners, lack of plotting skills and the lack of proficiency in the learners’ multiplication and division skills. This study made recommendations on the integration of multiple representative approaches in the mathematics education curriculum and textbooks. It further recommended that in-service workshops for teachers and student teachers on the integration of multiple representative approaches in the teaching of Grade 6 proportion word problems should be initiated.
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Iiyambo, Julia. "Investigating teachers’ experiences of using multiple representations to teach fractions for conceptual understanding in 'Grades 5-7': a Namibian case study." Thesis, Rhodes University, 2016. http://hdl.handle.net/10962/1296.
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This study investigated teachers’ experiences of using multiple representations to teach fractions for conceptual understanding in ‘grades 5 – 7’. Three teachers were involved in the study and the main goal was to explore how teachers might work with the additional tools of multiple representations to improve the teaching of fractions for conceptual understanding. Different types of multiple representations such as written mathematical symbols, descriptive written words, pictorial representations, manipulations, concrete reality, oral representations, and experience-based representations and videos or power point presentations were examined. This investigation was carried out through a focus group workshop developed by the researcher and though observations of fraction teaching which took place in schools. The research focused on the teachers working to develop their use of multiple representations to teach fractions and how they implemented what they learned in the workshop into their own classroom teaching. This study was conducted using a qualitative case study design and was oriented in the interpretive paradigm. The three participating teachers in the focus group workshop were observed and interviewed individually. The purpose of observing teaching before the workshop was to observe how the selected teachers taught fractions and in particular to observe which types of representations they used and how these were used to enhance the conceptual understanding of the learners. Post teaching took place after the focus group workshop and the different multiple representations which were used in different lessons were observed and analyzed. The purpose of the interview was to gain an understanding of the teachers’ views of using multiple representations when teaching fractions for conceptual understanding. The data showed that teachers who participated in the focus group workshop worked positively to develop their use of multiple representations to teach fractions. They made sense of fractions and were able to look at representations in different ways to develop the meaning and concepts of fractions. Teachers developed an understanding of working with multiple representations and were able to make connections among concepts and the use of concrete representations. Teachers also developed their lesson plans effectively to involve a variety of teaching methods and multiple representations, despite the limited time available to them. Moreover, teachers used different modes of representation to improve learner engagement in learning activities. Lastly, teachers used multiple representations to teach in ways that improved the learners’ conception of fractions. On the basis of this research, it can be concluded that in-service workshops for teachers on the integration of multiple representative tools in the teaching of ‘Grades 5 – 7’ fractions could provide a valuable contribution to further developing the teaching of fractions in schools.
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Bautista, Martín Miguel Ángel. "Learning error-correcting representations for multi-class problems." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/396124.
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Real life is full of multi-class decision tasks. In the Pattern Recognition field, several method- ologies have been proposed to deal with binary problems obtaining satisfying results in terms of performance. However, the extension of very powerful binary classifiers to the multi-class case is a complex task. The Error-Correcting Output Codes framework has demonstrated to be a very powerful tool to combine binary classifiers to tackle multi-class problems. However, most of the combinations of binary classifiers in the ECOC framework overlook the underlay- ing structure of the multi-class problem. In addition, is still unclear how the Error-Correction of an ECOC design is distributed among the different classes.
In this dissertation, we are interested in tackling critic problems of the ECOC framework, such as the definition of the number of classifiers to tackle a multi-class problem, how to adapt the ECOC coding to multi-class data and how to distribute error-correction among different pairs of categories.
In order to deal with this issues, this dissertation describes several proposals. 1) We define a new representation for ECOC coding matrices that expresses the pair-wise codeword separability and allows for a deeper understanding of how error-correction is distributed among classes. 2) We study the effect of using a logarithmic number of binary classifiers to treat the multi-class problem in order to obtain very efficient models. 3) In order to search for very compact ECOC coding matrices that take into account the distribution of multi-class data we use Genetic Algorithms that take into account the constraints of the ECOC framework. 4) We propose a discrete factorization algorithm that finds an ECOC configuration that allocates the error-correcting capabilities to those classes that are more prone to errors. The proposed methodologies are evaluated on different real and synthetic data sets: UCI Machine Learning Repository, handwriting symbols, traffic signs from a Mobile Mapping System, and Human Pose Recovery. The results of this thesis show that significant perfor- mance improvements are obtained on traditional coding ECOC designs when the proposed ECOC coding designs are taken into account.En la vida cotidiana las tareas de decisión multi-clase surgen constantemente. En el campo de Reconocimiento de Patrones muchos métodos de clasificación binaria han sido propuestos obteniendo resultados altamente satisfactorios en términos de rendimiento. Sin embargo, la extensión de estos sofisticados clasificadores binarios al contexto multi-clase es una tarea compleja. En este ámbito, las estrategias de Códigos Correctores de Errores (CCEs) han demostrado ser una herramienta muy potente para tratar la combinación de clasificadores binarios. No obstante, la mayoría de arquitecturas de combinación de clasificadores binarios negligen la estructura del problema multi-clase. Sin embargo, el análisis de la distribución de corrección de errores entre clases es aún un problema abierto. En esta tesis doctoral, nos centramos en tratar problemas críticos de los códigos correctores de errores; la definición del número de clasificadores necesarios para tratar un problema multi-clase arbitrario; la adaptación de los problemas binarios al problema multi-clase y cómo distribuir la corrección de errores entre clases. Para dar respuesta a estas cuestiones, en esta tesis doctoral describimos varias propuestas. 1) Definimos una nueva representación para CCEs que expresa la separabilidad entre pares de códigos y nos permite una mejor comprensión de cómo se distribuye la corrección de errores entre distintas clases. 2) Estudiamos el efecto de usar un número logarítmico de clasificadores binarios para tratar el problema multi-clase con el objetivo de obtener modelos muy eficientes. 3) Con el objetivo de encontrar modelos muy eficientes que tienen en cuenta la estructura del problema multi-clase utilizamos algoritmos genéticos que tienen en cuenta las restricciones de los ECCs. 4) Pro- ponemos un algoritmo de factorización de matrices discreta que encuentra ECCs con una configuración que distribuye corrección de error a aquellas categorías que son más propensas a tener errores. Las metodologías propuestas son evaluadas en distintos problemas reales y sintéticos como por ejemplo: Repositorio UCI de Aprendizaje Automático, reconocimiento de símbolos escritos, clasificación de señales de tráfico y reconocimiento de la pose humana. Los resultados obtenidos en esta tesis muestran mejoras significativas en rendimiento comparados con los diseños tradiciones de ECCs cuando las distintas propuestas se tienen en cuenta.
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Danielsson, Oscar. "Shape-based Representations and Boosting for Visual Object Class Detection : Models and methods for representaion and detection in single and multiple views." Doctoral thesis, KTH, Datorseende och robotik, CVAP, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-58479.
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Detection of generic visual object classes (i.e. cars, dogs, mugs or people) in images is a task that humans are able to solve with remarkable ease. Unfortunately this has proven a very challenging task for computer vision. Thereason is that different instances of the same class may look very different, i.e. there is a high intra-class variation. There are several causes for intra-class variation; for example (1) the imaging conditions (e.g. lighting and exposure) may change, (2) different objects of the same class typically differ in shape and appearance, (3) the position of the object relative to the camera (i.e. the viewpoint) may change and (4) some objects are articulate and may change pose. In addition the background class, i.e. everything but the target object class, is very large. It is the combination of very high intra-class variation with a large background class that makes generic object class detection difficult. This thesis addresses this challenge within the AdaBoost framework. AdaBoost constructs an ensemble of weak classifiers to solve a given classification task and allows great flexibility in the design of these weak classifiers. This thesis proposes several types of weak classifiers that specifically target some of the causes of high intra-class variation. A multi-local classifier is proposed to capture global shape properties for object classes that lack discriminative local features, projectable classifiers are proposed to handle detection from multiple viewpoints and finally gated classifiers are proposed as a generic way to handle high intra-class variation in combination with a large background class. All proposed weak classifiers are evaluated on standard datasets to allow performance comparison to other related methods.Vi människor kan utan ansträngning känna igen ett stort antal visuella objektklasser (såsom bilar, hundar, koppar eller människor). Tyvärr har det visat sig mycket svårt att programmera en dator att göra samma sak. Anledningen är att olika objekt från samma klass kan ha mycket olika utseende, beroende på att (1) avbildningsförutsättningar (exempelvis ljussättning och exponering) kan förändras, (2) olika objekt från samma klass har ofta mycket olika fysiska egenskaper (såsom färg, form eller material), (3) synvinkeln förändras och (4) rörliga objekt kan inta olika ställningar. Utöver detta är bakgrundsklassen, d.v.s. alla tänkbara bilder som inte föreställer ett objekt från målklassen, mycket stor. Det är kombinationen av hög intraklassvariation och stor bakgrundsklass som gör objektigenkänning till ett svårt problem. Denna utmaning bemöter vi inom ramarna för maskininlärningsmetoden AdaBoost. AdaBoost bygger en kraftfull klassificerare genom att kombinera ett stort antal svaga klassificerare, vars utformning är mycket fri. Denna avhandling behandlar flera olika typer av svaga klassificerare vars målsättning är att hantera några av orsakerna till intraklassvariation. Vi föreslår en multilokal klassificerare för att fånga icke-lokala formegenskaper hos objektklassersom saknar diskriminativa lokala egenskaper. Vi föreslår vidare projicerbara klassifierare för att hantera en varierande synvinkel. Slutligen föreslår vi en klassifierare baserad på logiska grindar som ett generiskt sätt att hantera stor intraklassvariation i kombination med stor bakgrundsklass. Vi utvärderar alla föreslagna svaga klassificerare på publika datamängder för att underlätta jämförelse med andra metoder.
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