Student Conceptions of Ionic Bonding: Patterns of thinking across three European contexts

Previous research has reported that students commonly develop alternative conceptions in the core topic of chemical bonding. Research in England has reported that students there commonly demonstrate an alternative ‘molecular’ conceptual framework for thinking about ionic bonding: in terms of the formation of molecule-like ions pairs through electron transfer, which are internally bonded, but not bonded to other ions. The present study reports the use of translated versions of a diagnostic instrument to elicit the conceptions of bonding in NaCl (commonly used as the teaching example of an ionic compound) from two samples of students setting out on university courses in Greece and Turkey. The study reports that students in these two contexts displayed high levels of support for statements based upon the alternative conceptual framework identified in the English context. Students commonly develop similar alternative conceptions of ionic bonding in these three different educational contexts. The study also found some quite large differences in the specific response patterns across these three contexts, some of which could reflect specific features of the different curriculum contexts. The study reinforces the cross-national nature of the challenge of effectively teaching the abstract models of chemistry at the submicroscopic level. It also provides intriguing suggestions that a close study of the interactions between specific curriculum contexts and specific patterns in students' thinking offers much potential for identifying particular aspects of subject pedagogy that either support or impede the learning of accepted scientific models.     

Making the invisible visible: enhancing students’ conceptual understanding by introducing representations of abstract objects in a simulation

This study aimed to identify if complementing representations of concrete objects with representations of abstract objects improves students’ conceptual understanding as they use a simulation to experiment in the domain of Light and Color. Moreover, we investigated whether students’ prior knowledge is a factor that must be considered in deciding when to use representations of abstract objects. A pre-post comparison study design was used, involving 69 participants assigned to two conditions. The first condition consisted of 36 students who had access to a simulation with representations of concrete objects, whereas the second condition consisted of 33 students who had access to a simulation with representations of both concrete and abstract objects. Both conditions used the same inquiry-oriented curriculum materials, consisting of three sections that included physical phenomena with increasingly complex underlying mechanisms, so that the third section’s mechanisms were more complex in nature than those in the first two sections. Tests were administered to assess students’ conceptual understanding before and after the presentation of the curricular material as a whole, as well as before and after each of its three sections. Results revealed that the presence of representations of abstract objects was helpful for the first two sections, but only for students with low prior knowledge. On the third, most complex section, also the students with higher prior knowledge profited from the presence of abstract objects. From these findings, we conjecture that for physical phenomena with a lower level of complexity, students with high prior knowledge are able to mentally construct the necessary abstract concepts on their own, whereas for higher levels of complexity they need an explicit representation of the abstract objects in the learning environment.     

International Approaches to Learning Disabilities: More Alike or More Different?

This special issue deals with the identification and remediation criteria/practices employed in several countries regarding learning disabilities (LD). An analysis of the identification criteria suggests that most countries follow early law mandates of the United States (e.g., PL 94–142) regarding the definition of the disorder and use the classical discrepancy between potential and achievement model for identification purposes (with few exceptions). Several countries reported the absence of standardized assessments and experts who can deal with the disorder, a fact that is more prominent in countries that have to deal with the education of minority/immigrant groups. Multicultural, political, linguistic, and economic factors seemed to influence both the identification practices and also the remediation services (quality and availability). By closely examining the factors deemed important for students with LD, it was obvious that most authors pointed to the importance of socio‐emotional variables. I concluded that these latter factors may be accountable, to a large extent, for the experience of students with LD at school and close attention needs to be paid to them.     

Virtual restoration of faces appearing in byzantine icons

Virtual restoration of cultural heritage (CH) artefacts is an important task that aims to digitally recreate the original appearance of damaged items. In this paper, a method that can be used for virtual restoration of faces appearing in damaged Byzantine icons is presented. Given a damaged face, the complete three-dimensional (3D) geometry of the face is reconstructed using data from the non-damaged facial parts and the texture of the damaged areas is restored. A key aspect of the proposed method is the use of a customized 3D deformable face model suitable for representing the geometry of Byzantine faces, the so-called Byzantine Style Specific Model (BSSM). A BSSM is generated by enforcing rule-based constraints on a deformable model trained using 3D scans of human faces. The use of a BSSM ensures that the Byzantine style is preserved during the process of shape restoration.     

Author Index

Authors Index

Author Index     

A study of group interaction processes in learning lower secondary physics

This study explores the effectiveness of a cooperative learning (CL) approach, where students work together and elaborate concepts of physics. The group problem‐solving tasks were conceptual questions from physics, where the students had to discuss and provide explanations of some phenomena. The effectiveness of the learning‐in‐groups approach was validated and correlated with working group interactiveness. Two group variables were assigned: the group performance and the group activity. These variables and the subjects' participation variable were correlated with achievement. Discourse analysis revealed variation in the nature of the interactions and information exchange, and the two roles as learners and learning facilitators. In addition, the study provided evidence for some features of cooperative learning that could characterize it as a nonlinear dynamical process. Implications of the findings are discussed. © 2006 Wiley Periodicals, Inc. J Res Sci Teach 43: 556–576, 2006     

Sound Practice and Practical Conservation Recipes as Described in Greek Post-Byzantine Painters’ Manuals

Post-medieval Greek painting manuals, exemplified by the Hermeneia of the Art of Painting by Dionysius of Fourna, were often copied, enriched, and widely used in icon-painter workshops until the twentieth century. These manuals reflect the accumulated experience of many generations of painters and include sections that pertain to preparation and application of materials and handling of works. Here we present, discuss, and, in some cases, compare with pertinent western instructions and experimental findings (deriving from the analysis of icons and wall paintings), key Greek manual instructions for sound practice, and practical conservation of paintings. Instructions in consideration come from both the published version of Hermeneia and various unpublished manuals; it is shown that the first part of the widely circulating standard edition of Dionysius is by no means an exhaustive account of post-Byzantine technical knowledge.     

Matthew effects in reading comprehension: myth or reality?

The presence of Matthew effects was tested in students of varying reading, spelling, and vocabulary skills. A cross-sequential design was implemented, following 587 Grade 2 through 4 students across five measurement points (waves) over 2 years. Students were administered standardized assessments of reading, spelling, and vocabulary. Results indicated that the hypothesized fan-spread pattern for Matthew effects was not evident. Low and high ability groups were formed based on 25th and 75th percentile cutoffs on initial measures of spelling, reading accuracy and fluency, vocabulary, and reading comprehension. Multilevel modeling suggested that low and high ability groups had significantly different starting points (intercepts) and their pattern of growth on passage comprehension did not indicate that the gap would increase over time. Instead, some analyses, especially of the youngest cohorts, showed significant convergence. However, there was no evidence of eventually closing the gap. Thus, although the poor students may not be getting poorer, they do not get sufficiently richer either.     

A results merging algorithm for distributed information retrieval environments that combines regression methodologies with a selective download phase

The problem of results merging in distributed information retrieval environments has gained significant attention the last years. Two generic approaches have been introduced in research. The first approach aims at estimating the relevance of the documents returned from the remote collections through ad hoc methodologies (such as weighted score merging, regression etc.) while the other is based on downloading all the documents locally, completely or partially, in order to calculate their relevance. Both approaches have advantages and disadvantages. Download methodologies are more effective but they pose a significant overhead on the process in terms of time and bandwidth. Approaches that rely solely on estimation on the other hand, usually depend on document relevance scores being reported by the remote collections in order to achieve maximum performance. In addition to that, regression algorithms, which have proved to be more effective than weighted scores merging algorithms, need a significant number of overlap documents in order to function effectively, practically requiring multiple interactions with the remote collections. The new algorithm that is introduced is based on adaptively downloading a limited, selected number of documents from the remote collections and estimating the relevance of the rest through regression methodologies. Thus it reconciles the above two approaches, combining their strengths, while minimizing their drawbacks, achieving the limited time and bandwidth overhead of the estimation approaches and the increased effectiveness of the download. The proposed algorithm is tested in a variety of settings and its performance is found to be significantly better than the former, while approximating that of the latter.