In network design, a communication network is optimized for a given set of parameters like cost, reliability and delay. This study analyzes network design problem using Genetic Algorithms in detail and makes comparison of different approaches and representations. Encoding of a problem is one of the most crucial design choices in Genetic Algorithms. For network design problem, this study compares adjacency matrix representation with list of edges representation. Also, another problem is defining a fair fitness function that will not favor one optimization parameter to the other. Multi-objective optimization is a recommended solution for such problems. This study describes and compares some of those approaches for different combinations in network design problem.

The purpose of this study was to investigate the effects of multiple representations-based instruction on seventh grade students&amp / #8217 / 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&amp / #8217 / attitudes towards mathematics, mathematics attitude scale, to determine students&amp / #8217 / 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&amp / #8217 / 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&amp / #8217 / 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.

The aim of the study is two fold: (1) to determine middle grade students&rsquo / abilities in translating among representations of fractions concept and (2) to investigate the effect of grade level and gender on students&rsquo / abilities in translating among representations. In this study the &ldquo / Translations among Representations Abilities Test (TRAT)&rdquo / was developed and used as a measuring instrument. The study was conducted in 19 randomly selected public elementary schools throughout Yenimahalle and &Ccedil / ankaya districts of Ankara with a total of 1456 sixth, seventh, and eight grade students in 2005-2006 fall semester. Each student&rsquo / s responses which were considered as incorrect were examined according to their grade levels. Based on the findings, the most frequent incorrect response types, the easiest, and the most difficult items were identified. In addition to these findings, two-way analysis of variance model (ANOVA) was used in order to investigate the effects of grade level and gender on students&rsquo / total scores on the TRAT. To the results of the examinations of students&rsquo / responses, it was seen that students&rsquo / abilities in translating among representations of fractions were low. The most frequent incorrect responses were seen in translations which include number line models and region models representing improper fractions. The lowest mean score was belonged to the sixth graders / while the highest mean score was belong to the eighth graders. Results of the statistical analyses revealed that grade level had a statistically significant main effect on students&rsquo / abilities in translating among representations. Additionally, it was seen that, female students had higher mean scores on the TRAT than males.

When interviewing school students for what constitutes a good mathematics teacher, the first characteristic usually listed is the ability to explain well. Besides well-founded content knowledge most important for classroom episodes of teacher explanations is knowledge about how to present mathematical concepts in a comprehensible way to students. This encompasses competencies in the area of verbal communication as well as the conscious use of means for illustrating and visualising mathematical ideas. We report about an analysis of explanatory processes in math lessons and about an analysis of prospective teachers\' explanatory competencies. As a result we identify improvements in teacher education at university.

No description available.

Advances in technology and the continued emergence of the Web as a major source of global information have encouraged tertiary educators to take advantage of this growing array of resources and move beyond traditional face-to-face and distance education correspondence modes toward a rich technology-mediated learning environment. Moreover, ready access to multimedia at the desk-top has provided an opportunity for educators to develop flexible, engaging and interactive learning resources incorporating multimedia and hypermedia. This study investigates pedagogical, individual and institutional factors influencing the adoption and integration of educational technology by academics at a regional Australian university for the purpose of developing interactive multimodal technology-mediated distance education courses. These courses include a range of multimodal learning objects and multiple representations of content in order to cater for different learning styles and modal preferences. The findings of this study revealed that a range of pedagogical, individual and institutional factors influence academics' development of interactive multimodal technology-mediated distance education courses. Implications for distance education providers and individual academics arising from these factors and subsequent recommendations are presented.

Bibliography: leaves 143-146 / vii, 147 leaves ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Mathematical Physics, 1986

Students of chemistry encounter difficulties due to its abstract nature and the need to understand and communicate its concepts on macro, submicro, and symbolic levels using a range of representations and representational modes. Research suggests that when students are required to use multiple representations they have difficulties in understanding individual representations and in negotiating meaning through their use. This study sought to address these issues through the application of digital technologies. The main areas of research that provided a theoretical framework for this study were multiple representations in chemistry education and writing-to-learn in science. Other research in these areas has suggested that a better understanding of multiple representations might enhance students’ chemical literacy; however, limited research has investigated the impact of using digital technologies to create multimodal texts on students’ learning in chemistry, particularly the development of students’ skills in generating and integrating multiple representations. Until recently, much of the writing-to-learn research has focused on written composition. The knowledge-transforming model was proposed by Bereiter and Scardamalia (1987) to explain the influence of written composition on knowledge construction. However, having been developed prior to the time when students had ready access to digital technologies and a consequent capacity to create multimedia and digital texts, this model does not account for the production of such multimodal texts. This study examined the effect of learning experiences that utilised digital technologies to support students in using multiple representations and through writing-to-learn activities to create multimodal texts on learning outcomes in chemistry. The study was conducted in a metropolitan public co-educational high school in Queensland, Australia. Two Year 11 chemistry classes participated in the study, which was conducted in the first term of a 2-year course in which students learn chemistry as a separate discipline. The study consisted of a pilot study and an intervention study with two phases. The pilot study was used to trial the learning activities and data collection instruments and to gain an insight into instructional approaches that might be appropriate for the study. Phase 1 of the intervention study employed a pretest–posttest design. In this phase, students learned about chemical bonding and structure and their effects on the properties and behaviours of different materials. They also learned about the multiple representations used to understand and communicate about chemical bonding and structure. Within a modified crossover design, Phase 2 of the study employed mixed methods to compare the effects on learning outcomes when they created two different scientific texts: a digital poster and a laboratory report. Both text types required students to integrate multiple representations to report on their learning during laboratory investigations. These text types were chosen because they are commonly used by scientists to communicate their experimental findings. In Phase 1, students engaged in computer-based inquiries using both molecular modelling and simulation software to investigate phenomena such as intra- and inter-molecular bonding and their effects on properties, the differences between various types of bonds, the multiple representations used to describe and investigate bonding and structure, and to present their understanding to others. In Phase 2, students used a range of scaffolding resources to design and carry out two inquiries about the chemistry of biomaterials. In the first inquiry, students made and compared the properties of two different bioplastic films; in the second, students compared the relative fermentation rates of a range of carbohydrates. In both inquiries, students were required to report their findings and explain them on the submicro level using appropriate representations. Scaffolds included Science Writing Heuristics, which explicitly required students to consider which multiple representations would support their claims and explanations of data; digital resources for selecting, modifying, or creating representations; and genre templates. Pretest–posttest comparisons for both phases showed that the instructional approaches and resources used were effective for enhancing students’ learning outcomes. In all comparisons, the posttest performances were significantly higher. In the first phase, several of the identified alternative or missing conceptions about chemical bonding were effectively addressed, and in both phases, students’ conceptual understanding and their representational competencies were enhanced. The pretest–posttest comparisons for Phase 2 suggested that creating a diversified text – a digital poster – for explaining experimental results is at least as effective for enhancing understanding and representational competencies as creating a more traditional laboratory report. Other data were analysed to gain an insight into how or why the instructional strategies and resources used might have been effective. The student interviews revealed a number of advantages of using digital technologies, including promotion of higher order thinking, enhanced motivation and interest, the capacity of digital technologies to support and enhance visualisation, and the production of multiple representations in multiple modes. Students suggested that the digital resources allowed them to make links between macroscopic, molecular, and symbolic levels and to include a range of representations in their explanations. The evaluation questionnaire revealed similar trends. Analysis of the students’ texts suggested that the approaches used in Phase 2 were effective in supporting students’ content and rhetorical problem solving and the interactions between the two. Students utilised a range of representations, particularly structural diagrams, when making explanations of their macroscopic data on the submicro level. This study has implications for the instructional approaches used by chemistry teachers because it showed that integrating digital technologies into learning environments is effective when introducing students to the multiple representations used in chemistry and in the development of students’ chemical literacies. It also contributes to writing-to-learn research by focusing on multimodal communication and the benefits of creating multimodal texts for presenting, organising, and explaining data, and for representing knowledge. Significant findings of the study relate to the importance of digital technologies in generating multimodal texts and representations for instruction, scaffolding, and in student-centred inquiry-based learning. Further research might focus on the use of such resources for addressing other commonly identified alternative conceptions, the creation of other multimodal text types, the use of other digital technologies or authoring tools, or on the development of teachers’ technological pedagogical content knowledge, which is required for effective classroom implementation of these resources and strategies.

This study examines the social representations of Thailand’s tourism development and related social impact, as perceived by respondents from Bangkok, Thailand. Employing social representations theory (SRT) and social exchange theory (SET), this study adopts qualitative methods to obtain respondents’ representations of tourism development in Bangkok. For the study, forty in-depth interviews and four focus-group interviews were conducted with respondents who were either involved or not involved in the tourism industry. The two main issues considered were, firstly, the determination of the concepts used to perceive tourism development and its social impact among Thai people and, secondly, how social exchanges affected these perceptions. The research suggests that there are four clusters of respondents who share common perceptions and certain socio-economic characteristics. Cluster one: respondents in this cluster are highly involved in tourism and are mostly of high socio-economic status. They share perceptions of Thailand’s tourism development as moving slowly forward, but hampered by red-tape management and bureaucratic problems. This cluster views economic impact in a positive light, especially with regard to the country’s increased revenue, and they perceive of culture as a tourism product. This group viewed environmental impact as a global problem and they mostly expressed the view that the tourism industry has a social responsibility to reduce the causes of pollution. Cluster two: respondents in this cluster are not involved in tourism and have a high socio-economic status. They perceive tourism development as having both positive and negative aspects. Economic impacts were represented both positively, in terms of national revenues and job creation, and negatively, in terms of fostering a materialistic society. Generally, this cluster views the social impact of tourism more negatively. Cluster three: respondents in this cluster are in mid-level-management positions in industries both involved and not involved in the tourism industry. They perceive tourism development in both positive and negative terms. They have favourable views of the economic impact of tourism and view Thai culture as a tourism product. Some respondents in this cluster are concerned about the environmental impact of tourism. Cluster four: respondents in this cluster have a low socio-economic status and include those involved and not involved in the tourism industry. This cluster perceived tourism development in positive terms. They predominantly viewed tourism development as a way to modernise society. This study also found six factors that affect individuals’ social representations of tourism development and social impact: personal benefits, socio-economic background, cultural values, personal traits, and socially derived and direct experiences. Of these, four were intrinsic factors—personal traits, direct experiences, individual benefits, and socio-economic backgrounds. The remaining two - socially derived and cultural values - were extrinsic factors. This study found that extrinsic factors are the main sources of individual representations and lead to hegemonic social representations. The significance and contribution of this research lies in two categories—theoretical and practical. From the theoretical angle, this research makes a number of contributions to the body of knowledge of social representation and social exchange. In terms of a practical contribution, these results can assist the Thai government to review the issues raised and ultimately provide more effective management.

Students of chemistry encounter difficulties due to its abstract nature and the need to understand and communicate its concepts on macro, submicro, and symbolic levels using a range of representations and representational modes. Research suggests that when students are required to use multiple representations they have difficulties in understanding individual representations and in negotiating meaning through their use. This study sought to address these issues through the application of digital technologies. The main areas of research that provided a theoretical framework for this study were multiple representations in chemistry education and writing-to-learn in science. Other research in these areas has suggested that a better understanding of multiple representations might enhance students’ chemical literacy; however, limited research has investigated the impact of using digital technologies to create multimodal texts on students’ learning in chemistry, particularly the development of students’ skills in generating and integrating multiple representations. Until recently, much of the writing-to-learn research has focused on written composition. The knowledge-transforming model was proposed by Bereiter and Scardamalia (1987) to explain the influence of written composition on knowledge construction. However, having been developed prior to the time when students had ready access to digital technologies and a consequent capacity to create multimedia and digital texts, this model does not account for the production of such multimodal texts. This study examined the effect of learning experiences that utilised digital technologies to support students in using multiple representations and through writing-to-learn activities to create multimodal texts on learning outcomes in chemistry. The study was conducted in a metropolitan public co-educational high school in Queensland, Australia. Two Year 11 chemistry classes participated in the study, which was conducted in the first term of a 2-year course in which students learn chemistry as a separate discipline. The study consisted of a pilot study and an intervention study with two phases. The pilot study was used to trial the learning activities and data collection instruments and to gain an insight into instructional approaches that might be appropriate for the study. Phase 1 of the intervention study employed a pretest–posttest design. In this phase, students learned about chemical bonding and structure and their effects on the properties and behaviours of different materials. They also learned about the multiple representations used to understand and communicate about chemical bonding and structure. Within a modified crossover design, Phase 2 of the study employed mixed methods to compare the effects on learning outcomes when they created two different scientific texts: a digital poster and a laboratory report. Both text types required students to integrate multiple representations to report on their learning during laboratory investigations. These text types were chosen because they are commonly used by scientists to communicate their experimental findings. In Phase 1, students engaged in computer-based inquiries using both molecular modelling and simulation software to investigate phenomena such as intra- and inter-molecular bonding and their effects on properties, the differences between various types of bonds, the multiple representations used to describe and investigate bonding and structure, and to present their understanding to others. In Phase 2, students used a range of scaffolding resources to design and carry out two inquiries about the chemistry of biomaterials. In the first inquiry, students made and compared the properties of two different bioplastic films; in the second, students compared the relative fermentation rates of a range of carbohydrates. In both inquiries, students were required to report their findings and explain them on the submicro level using appropriate representations. Scaffolds included Science Writing Heuristics, which explicitly required students to consider which multiple representations would support their claims and explanations of data; digital resources for selecting, modifying, or creating representations; and genre templates. Pretest–posttest comparisons for both phases showed that the instructional approaches and resources used were effective for enhancing students’ learning outcomes. In all comparisons, the posttest performances were significantly higher. In the first phase, several of the identified alternative or missing conceptions about chemical bonding were effectively addressed, and in both phases, students’ conceptual understanding and their representational competencies were enhanced. The pretest–posttest comparisons for Phase 2 suggested that creating a diversified text – a digital poster – for explaining experimental results is at least as effective for enhancing understanding and representational competencies as creating a more traditional laboratory report. Other data were analysed to gain an insight into how or why the instructional strategies and resources used might have been effective. The student interviews revealed a number of advantages of using digital technologies, including promotion of higher order thinking, enhanced motivation and interest, the capacity of digital technologies to support and enhance visualisation, and the production of multiple representations in multiple modes. Students suggested that the digital resources allowed them to make links between macroscopic, molecular, and symbolic levels and to include a range of representations in their explanations. The evaluation questionnaire revealed similar trends. Analysis of the students’ texts suggested that the approaches used in Phase 2 were effective in supporting students’ content and rhetorical problem solving and the interactions between the two. Students utilised a range of representations, particularly structural diagrams, when making explanations of their macroscopic data on the submicro level. This study has implications for the instructional approaches used by chemistry teachers because it showed that integrating digital technologies into learning environments is effective when introducing students to the multiple representations used in chemistry and in the development of students’ chemical literacies. It also contributes to writing-to-learn research by focusing on multimodal communication and the benefits of creating multimodal texts for presenting, organising, and explaining data, and for representing knowledge. Significant findings of the study relate to the importance of digital technologies in generating multimodal texts and representations for instruction, scaffolding, and in student-centred inquiry-based learning. Further research might focus on the use of such resources for addressing other commonly identified alternative conceptions, the creation of other multimodal text types, the use of other digital technologies or authoring tools, or on the development of teachers’ technological pedagogical content knowledge, which is required for effective classroom implementation of these resources and strategies.