High‐school students’ reasoning while constructing plant growth models in a computer‐supported educational environment

This paper highlights specific aspects of high‐school students’ reasoning while coping with a modeling task of plant growth in a computer‐supported educational environment. It is particularly concerned with the modeling levels (‘macro‐phenomenological’ and ‘micro‐conceptual’ level) activated by peers while exploring plant growth and with their ability to shift between or within these levels. The focus is on the types of reasoning developed in the modeling process, as well as on the reasoning coherence around the central concept of plant growth. The findings of the study show that a significant proportion of the 18 participating dyads perform modeling on both levels, while their ability to shift between them as well as between the various elements of the ‘micro‐conceptual’ level is rather constrained. Furthermore, the reasoning types identified in peers’ modeling process are ‘convergent’, ‘serial’, ‘linked’ and ‘convergent attached’, with the first type being the most frequent. Finally, a significant part of the participating dyads display a satisfactory degree of reasoning ‘coherence’, performing their task committed to the main objective of exploring plant growth. Teaching implications of the findings are also discussed.     

‘Scaffolding’ through talk in groupwork learning

In the present study, we develop and deploy a conceptual framework of “scaffolding” in groupwork learning, through the analysis of the pursuit of a learning goal over time. The analysis follows individuals’ different experiences of an interaction as well as collective experiences, considering individual attainment as a result of a bi-directional contextualized conversation and action. We detect, describe and evaluate two (2) types of interaction that can be characterized as “scaffolding process”: the first concerns “Scaffolding individual thinking” and the second “Scaffolding collective thinking”. The latter, apart from presenting the educational advantages of collective thinking through peer discussion (D) and curriculum-focused evaluation context of Teacher Initiation – Student Response – Teacher Follow up (IRF), also presents the advantage of ‘spiral’ verbal exchanges in which the teacher “tunes in” to the students’ present state of ability or understanding (spiral IDRF).     

Dempster-Shafer Theory for a Query-Biased Combination of Evidence on the Web

This paper reports on a large-scale experiment for the evaluation of a formal query-biased combination of evidence mechanism. We use the Dempster-Shafer theory of evidence to combine optimally results obtained by content and link analyses on the Web. The query-biased mechanism is based on the query scope, a measure of the query specificity. The query scope is defined using a probabilistic propagation mechanism on top of the hierarchical structure of concepts provided by WordNet. We use two standard Web test collections and two different link analysis approaches. The results show that the proposed approach could improve the retrieval effectiveness.     

Performance analysis of distributed information retrieval architectures using an improved network simulation model

The increasing number of documents that have to be indexed in different environments, particularly on the Web, and the lack of scalability of a single centralised index lead to the use of distributed information retrieval systems to effectively search for and locate the required information. In this study, we present several improvements over the two main bottlenecks in a distributed information retrieval system (the network and the brokers). We extend a simulation network model in order to represent a switched network. The new simulation model is validated by comparing the estimated response times with those obtained using a real system. We show that the use of a switched network reduces the saturation of the interconnection network, especially in a replicated system, and some improvements may be achieved using multicast messages and faster connections with the brokers. We also demonstrate that reducing the partial results sets will improve the response time of a distributed system by 53%, with a negligible probability of changing the system’s precision and recall values. Finally, we present a simple hierarchical distributed broker model that will reduce the response times for a distributed system by 55%.     

Using educational software to support collective thinking and test hypotheses in the computer science curriculum

This study analyses the discourse among the teacher and the students, members of three (3) small groups, who learn in the environment of a stand-alone computer. Two educational environments are examined: the first one, a “virtual laboratory” (Virtual scale-DELYS) and the second one, a computer modeling environment (ModelsCreator). The ‘Virtual Scale’ environment provides users with curriculum focused feedback and in that sense it can be categorized as directive. The ModelsCreator environment provides users merely with a representation of their own conception of curriculum concepts, so it can be categorized as an open-ended environment. The goal of this research is to exemplify the way the two educational software environments support (a) the development of collective thinking in peer— and teacher-led discussion and (b) students’ autonomy. The software tools of the “Virtual scale” along with the resources provided for the problem solving created an educational framework of hypothesis testing. This framework did not limit the students’ contributions by directing them to give short answers. Moreover, it supported the students’ initiatives by providing tools, representations and procedures that offered educationally meaningful feedback. Based on the above results, we discuss a new educationally important structure of software mediation and describe the way the two software activities resourced collective thinking and students’ initiatives. Finally, for each type of software environment, we propose certain hypotheses for future research regarding the support of collaborative problem solving.     

The effective combination of hybrid usability methods in evaluating educational applications of ICT: Issues and challenges

This paper focuses on usability evaluation of information and communication technologies applications in education (ICTE applications). Various classes of teaching and learning systems are discussed in terms of technologies used and pedagogical approaches. Their usability is analyzed according to various dimensions and the impact of system usability on the learning effectiveness is studied. We argue that various classes of ICTE applications such as multimedia/hypermedia applications, open educational environments and CSCL environments, based on different theoretical perspectives, require fundamentally different approaches in evaluating their usability. The paper is structured as follows: an overview of different usability evaluation approaches is presented first, followed by a discussion on applicability of these techniques in various categories of teaching and learning computer systems. Typical case studies that engage both usability experts and users themselves (students and teachers) are also discussed. The objective is to describe both the methods, and the way to apply them effectively in order to certify the usability of an ICTE application with respect to its teaching and learning objectives.     

History of Science and Instructional Design: The Case of Electromagnetism

Science &; Education - This paper deals with two main research questions: a) Can we search for pupils' potential alternative ideas in the history of science and especially in those areas...