Enhancing Conceptual Change in Preschool Children’s Representations of Light: A Sociocognitive Approach

The aim of this study is to investigate the effect of a sociocognitive teaching strategy on young children’s understanding of light. It explores their understanding of the concept of light as an entity that is transmitted independently of the light source and the final receiver. The study was conducted in three phases: pretest, teaching intervention, and post-tests. The sample consisted of 170 preschool children who were assigned to two groups. The children in the first group participated in activities which adopted a sociocognitive approach. In the context of this approach, a familiar metaphor was introduced in order to facilitate children to construct a “precursor model” about light. The children in the second group participated in activities with the same teaching objectives, but adopting an empiricist perspective. Statistical analysis using the Mann–Whitney U test indicated that the cognitive progress of the sociocognitive group was more significant than the progress of the empiricist group. This provides evidence for the effect of the sociocognitive strategy on enhancing children in constructing a “precursor model” for the concept of light.     

Adaptation of the Students' Motivation Towards Science Learning (SMTSL) questionnaire in the Greek language

The present study aimed at adapting in the Greek language the Students' Motivation Towards Science Learning (SMTSL) questionnaire developed by Tuan, Chin, and Shieh (INT J SCI EDUC 27(6): 639-654, 2005a) into a different cultural context, a different age group, that is, in university students and with a focus on physics learning. Three hundred and fifty Greek student teachers participated in the study. The original instrument consisted of 35 items allocated in six scales: self-efficacy, use of active learning strategies, science learning value, performance goals, achievement goals, and learning environment stimulation. The instrument's internal consistency was acceptable and comparable to previous studies' reports. Confirmatory factor analysis (CFA) was applied on the data in order to test an a priori hypothesis regarding the SMTSL's factorial structure based on previous studies' findings. The results of the study showed that the six-factor conceptual model of students' motivation proposed by the SMTSL applies in this different cultural setting and in this group of university students with reference to physics learning. Along with the six distinct motivational constructs confirmed, students' motivational beliefs were also explained by a general motivational construct assumed to be at their basis. Suggestions for further improvement of the Greek version of the SMTSL are also discussed.     

Subspace design of low-rank estimators for higher-order statistics

Higher-order statistics (HOS) are well known for their robustness to additive Gaussian noise and ability to preserve phase. HOS estimates, on the other hand, have been criticized for high complexity and the need for long data in order to maintain small variance. Since rank reduction offers a general principle for reduction of estimator variance and complexity, we consider the problem of designing low-rank estimators for HOS. We propose three methods for choosing the transformation matrix that reduces the mean-square error (MSE) associated with the low-rank HOS estimates. We also demonstrate the advantages of using low-rank third-order moment estimates for blind system estimation. Results indicate that the full rank MSE corresponding to some data length N can be attained by a low-rank estimator corresponding to a length significantly smaller than N.     

Contradictions,dialectical oppositions and shifts in teaching mathematics

The study reported in this paper concerns the tensions and conflicts that teachers experience while they enact a new set of reform-oriented curricular materials into their classrooms. Our focus is οn the interactions developed in two groups of teachers in two schools for a period of a school year. We use Activity Theory to study emerging contradictions and we elaborate on the construct of dialectical opposition to understand the nature of these contradictions and their potential for teacher learning. We provide evidence that discussions about contradictions and their dialectical character in the two groups support teachers to engage differently in mathematics teaching and learning and carry potentials for shifts in the practices that evolve in their classrooms. Our study addresses empirically in the context of mathematics teaching the philosophical claim about the role of contradictions as a driving force for any dynamic system.     

Study of the stability of a series of synthetic colorants applied with styrene-acrylic copolymer, widely used in contemporary paintings, concerning the effects of accelerated ageing

This study examines the materials of a contemporary pictorial artwork, belonging to the Macedonian Museum of Contemporary Art in Thessaloniki (Greece), and needing conservation. The combined use of micro-FTIR and micro-Raman spectroscopy allowed the identification of almost all painting materials. Moreover, the stability of a series of synthetic pigments towards accelerated ageing is investigated in applications using the contemporary binding medium styrene-acrylic copolymer. The pigments in question are: Hansa yellow PY3 and PY74, quinacridone PV19 and PR122, naphthol AS PR112, phthalocyanine green PG7 and blue PB15, dioxazine PV37, van Dyck brown PBk11, ivory black PBk9, and titanium dioxide PW6. The organic pigments were applied alone or mixed with titanium dioxide, in rutile form or as a mixture of rutile/anatase. The experimental swatches were subjected to ageing tests, and subsequently studied as to colour changes by means of colorimetric measurements, and as to the molecular structure differentiations by infrared spectroscopy in reflectance mode. The ageing tests included exposure to high temperature and humidity (90 °C, 60% RH) and to ultraviolet radiation (350 nm, 30 °C and 50% RH, with a substantial temperature increase at 90 °C for 3 days). The greater colour difference is caused by high temperature and humidity, whereas paint layers containing TiO₂, and especially the mixture of the forms rutile/anatase, prove very susceptible to ultraviolet radiation, demonstrating a significant colour difference and extended molecular changes.     

The influence of water depth on kinematic and spatiotemporal gait parameters during aquatic treadmill walking

The purpose of this study was to investigate kinematic and spatiotemporal variables of aquatic treadmill walking at three different water depths. A total of 15 healthy individuals completed three two-minute walking trials at three different water depths. The aquatic treadmill walking was conducted at waist-depth, chest-depth and neck-depth, while a customised 3-D underwater motion analysis system captured their walking. Each participant’s self-selected walking speed at the waist level was used as a reference speed, which was applied to the remaining two test conditions. A repeated measures ANOVA showed statistically significant differences among the three walking conditions in stride length, cadence, peak hip extension, hip range of motion (ROM), peak ankle plantar flexion and ankle ROM (All p values < 0.05). The participants walked with increased stride length and decreased cadence during neck level as compared to waist and chest level. They also showed increased ankle ROM and decreased hip ROM as the water depth rose from waist and chest to the neck level. However, our study found no significant difference between waist and chest level water in all variables. Hydrodynamics, such as buoyancy and drag force, in response to changes in water depths, can affect gait patterns during aquatic treadmill walking.     

Physical fitness normative values for 6–18-year-old Greek boys and girls,using the empirical distribution and the lambda,mu, and sigma statistical method

The aim of the this study was to establish age- and gender-specific physical fitness normative values and to compare percentiles and Z scores values in a large, nationwide sample of Greek children aged 6–18 years. From March 2014 to May 2014, a total of 424,328 boys and girls aged 6–18 years who attended school in Greece were enrolled. The studied sample was representative, in terms of age–sex distribution and geographical region. Physical fitness tests (i.e. 20?m shuttle run test (SRT), standing long jump, sit and reach, sit-ups, and 10?×?5?m SRT) were performed and used to calculate normative values, using the percentiles of the empirical distributions and the lambda, mu, and sigma statistical method. Normative values were presented as tabulated percentiles for five health-related fitness tests based on a large data set comprising 424,328 test performances. Boys typically scored higher than girls on cardiovascular endurance, muscular strength, muscular endurance, and speed/agility, but lower on flexibility (all p values <0.001). Older boys and girls had better performances than younger ones (p?相似文献   

Changes in school mathematics knowledge in Greece: a Bernsteinian analysis

The purpose of this paper is to critically examine the changes that took place in school mathematics knowledge for pupils aged six and seven (first grade of Greek elementary school) and its pedagogical approach, which took shape following the reforms of the mathematics curricula in 1982 and 2003. Our analysis is based on Bernstein’s theoretical framework on pedagogic discourse and Dowling’s theoretical framework on textual domains. The results showed that there are differences between the 1982 and 2003 reforms, in terms both of the content of mathematics knowledge, as well as of the forms of pedagogic interaction between the teacher and the pupil.     

Contemporary school knowledge democracy: possible meanings,promising perspectives and necessary prerequisites

ABSTRACT

The basic aim of this paper is to discuss the concept ‘Knowledge Democracy’ (KD) and what it can mean in the school context, its implications on knowledge production and dissemination and on the educational practices. We try to enrich this discussion by presenting action research projects to provide case studies of how thinking about KD can reshape educational practice. We consider that the discussion on KD has to be enriched as the concept seems very promising with good prospects towards school’s democratization. On the other hand, as it is quite new, it can encompass internal contradictions that can cause problems at the level of practice. So, we consider very important any contribution to this discussion not as another theoretical sample of the debate on the ‘politics of knowledge’, but because any improvement at the thinking of the issue can be reflected on school practices. Any challenge to traditional politics of knowledge can lead to a deeper understanding of the world of schooling and to transformations through new discourses and new approaches to teaching and learning in school.     

The transition to secondary school geometry: can there be a “chain of school mathematics”?

Students mainly perceive the transition to secondary school as an opportunity to start their school career anew. Reality often proves them wrong, especially in the case of mathematics. In our paper, we briefly discuss children’s transition to secondary school as both an opportunity and a problem, with reference to the Greek context. In discussions about the transition to secondary school and its effect on the teaching and learning of mathematics, primary and secondary school teachers in Greece often depict school mathematics as a “chain” of concepts and procedures. With this metaphor as our reference point, we discuss how ideologies about the teaching of mathematics are enacted in both school levels. We will base our discussion on the analysis of extracts taken from dialogues in primary and secondary school mathematics classrooms in Greece. In our analysis, we employ a Peircean view of semiotics in an attempt to conceptualize students’ rushed introduction to rigor in justifying mathematical statements in secondary school. These extracts are part of a longitudinal study that aimed, on the one hand, to pinpoint discontinuities and continuities in the teaching of geometry between primary and secondary schools and, on the other, to investigate whether a set of curriculum material that we designed could serve as a link in the teaching of geometry between the two school levels.