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Multiple external representations (MERs) are useful for teaching complex content in science education. An open question is whether there is an especially effective way to sequence MERs. On the one hand, the so‐called concreteness fading approach suggests starting instruction with more concrete representations and proceeding stepwise to more idealized representations. The effectiveness of this fading approach is, however, supported mainly by studies in mathematics education, while the results in physics are equivocal. On the other hand, presenting different representations simultaneously may support linking, that is, the comparison and contrast of representations, which may benefit learning. In an experimental classroom study (N = 187), we compared concreteness fading and simultaneous presentation of MERs for learning a challenging physics content in high school, namely, Faraday's law. We found no significant differences between conditions in posttest performance, and an equivalence test with bounds d = −0.5 to 0.5 showed that both approaches performed equally. The results align with previous findings questioning the superiority of concreteness fading over other ways of sequencing MERs. Therefore, facilitating students' understanding of a complex physics content may involve more than determining the optimal order of presenting MERs. We discuss limitations of the present study and implications for future research and practice. [ABSTRACT FROM AUTHOR]

A review on the hydrogen reduction kinetics of NiO, NiCO3, and Ni(OH)2 hydrogen was conducted, and the most significant experimental values and results were summarized from the past two decades. Isothermal hydrogen reduction experiments of NiO, NiCO3, and, Ni(OH)2 experiments were carried out at 300 °C, 400 °C, and 500 °C, and the obtained data were fitted to multiple different solid-state kinetic models in order to compare the suitability of the models. Non-isothermal reduction in H2 (0 °C → 900 °C) showed the decomposition of NiCO3 at a temperature range of 230 °C to 300 °C and Ni(OH)2 at 220 °C to 300 °C. The calculated Ea values for NiCO3, Ni(OH)2, and NiO varied between 30 and 35, 36 and 37, and 21 and 26 kJ/mol, respectively. Most of the used models were well fitted making the choice of unequivocally the best suitable model difficult and the identification of the mechanism behind the reaction. It was concluded that an increase in temperature accelerates the reduction process, and the reaction rate-controlling mechanism requires more extensive investigation. [ABSTRACT FROM AUTHOR]

Several research projects are currently focused on the search for new sources of scandium due to its expected increasing demand in advanced technology applications. The Kiviniemi Fe-Sc-enriched mafic intrusion is a potential primary source for Sc. According to the recent investigations on the FeO component reduction in the Kiviniemi magnetic Sc concentrate at various end temperatures, complete FeO reduction is achieved at the highest experimental temperature (1500 °C). However, efficient separation of metal from the Sc2O3-enriched slag is hindered by the high viscosity of the slag. In this study, investigations of the Kiviniemi-type concentrate reduction characteristics are complemented from three perspectives: (1) slag modification with CaF2 and/or CaO to promote the reduction of the FeO component and metal separation, (2) reduction characteristics of the concentrates with a slightly different modal mineralogy and chemical composition, and (3) description of the main features of the progression of reduction at selected temperatures (950, 1050, 1150, 1250, and 1350 °C) with CaO addition. Both CaF2 and CaO increase conversion rates at a lower temperature region and promote the separation of metal from the slag. High-temperature behavior of the concentrates used in this study is essentially similar, although the main reduction stage is initiated at a slightly higher temperature for concentrates with less amphibole and a higher amount of nonferrous gangue minerals. Only after the complete decomposition and melting of clinopyroxene and nonferrous minerals of the concentrate, the final reduction of the FeO component from the slag can take place. [ABSTRACT FROM AUTHOR]

To help students acquire mathematics and science knowledge and competencies, educators typically use multiple external representations (MERs). There has been considerable interest in examining ways to present, sequence, and combine MERs. One prominent approach is the concreteness fading sequence, which posits that instruction should start with concrete representations and progress stepwise to representations that are more idealized. Various researchers have suggested that concreteness fading is a broadly applicable instructional approach. In this theoretical paper, we conceptually analyze examples of concreteness fading in the domains of mathematics, physics, chemistry, and biology and discuss its generalizability. We frame the analysis by defining and describing MERs and their use in educational settings. Then, we draw from theories of analogical and relational reasoning to scrutinize the possible cognitive processes related to learning with MERs. Our analysis suggests that concreteness fading may not be as generalizable as has been suggested. Two main reasons for this are discussed: (1) the types of representations and the relations between them differ across different domains, and (2) the instructional goals between domains and subsequent roles of the representations vary. [ABSTRACT FROM AUTHOR]

Active learning yields better learning outcomes than traditional, lecture-based teaching. Common approaches in large lecture courses are activating elements during the lectures and warm-up activities using online learning environments. However, implementing warm-up exercises, on which students work on by themselves makes formative feedback increasingly important. We have studied students' views on warm-up online exercises, focusing on the role of automated feedback. We compared two types of feedback: feedback which guided the student towards the correct answer and feedback that guided the student towards the correct reading materials. We have also examined the correlation between students' views on the exercises and learning outcomes, as measured by exercise and exam points. The exercises were administered with a Moodle-based system focusing on teaching and assessment using a computer-based algebra kernel. The study was conducted during the first introductory mechanics course in physics at the University of Helsinki. We concluded that the preferred type of feedback was dependent on the student, i.e. different students prefer different kinds of feedback. Importantly, the students who completed the exercises alone reported benefiting more from them, which shows that the warm-up exercises successfully extended support for students outside of classroom hours. [ABSTRACT FROM AUTHOR]

One well-known learning obstacle is that students rarely use the concepts in the way that scientists use them. Rather, students mix up closely related concepts and are inclined towards matter-based conceptualisations. Furthermore, some researchers have argued that certain difficulties are rooted in the student’s limited repertoire of causal schemes. These two aspects are conveniently represented in the recent proposal of the systemic view of concept learning. We applied this framework in our analyses of university students’ explanations of DC circuits and their use of concepts such as voltage, current and resistance. Our data consist of transcribed group interviews, which we analysed with content analysis. The results of our analysis are represented with directed graphs. Our results show that students had a rather refined ontological knowledge of the concepts. However, students relied on rather simple explanation models, but few students were able to modify their explanations during the interview. Based on the analysis, we identified three processes of change: model switch, model refinement and model elaboration. This emphasises the importance of relevant relational knowledge at a later stage of learning. This demonstrates how concept individuation and learning of relational structures occurs (and in which order) and sets forth interesting research questions for future research. [ABSTRACT FROM AUTHOR]

Model-based learning (MBL) has an established position within science education. It has been found to enhance conceptual understanding and provide a way for engaging students in authentic scientific activity. Despite ample research, few studies have examined the cognitive processes regarding learning scientific concepts within MBL. On the other hand, recent research within cognitive science has examined the learning of so-called relational categories. Relational categories are categories whose membership is determined on the basis of the common relational structure. In this theoretical paper, I argue that viewing models as relational categories provides a well-motivated cognitive basis for MBL. I discuss the different roles of models and modeling within MBL (using ready-made models, constructive modeling, and generative modeling) and discern the related cognitive aspects brought forward by the reinterpretation of models as relational categories. I will argue that relational knowledge is vital in learning novel models and in the transfer of learning. Moreover, relational knowledge underlies the coherent, hierarchical knowledge of experts. Lastly, I will examine how the format of external representations may affect the learning of models and the relevant relations. The nature of the learning mechanisms underlying students' mental representations of models is an interesting open question to be examined. Furthermore, the ways in which the expert-like knowledge develops and how to best support it is in need of more research. The discussion and conceptualization of models as relational categories allows discerning students' mental representations of models in terms of evolving relational structures in greater detail than previously done. [ABSTRACT FROM AUTHOR]

The process of learning scientific knowledge from the dynamic systems viewpoint is studied in terms probabilistic learning model (PLM), where learning accrues from foraging in the epistemic landscape. The PLM leads to the formation of attractor-type regions of preferred models in an epistemic landscape. The attractor-type states correspond to robust learning outcomes which are more probable than others. These can be assigned either to the high confidence in model selection or to the dynamic evolution of a learner's proficiency, which depends on the learning history. The results suggest that robust learning states are essentially context dependent, and that learning is a continuous development between these context dependent states. © 2016 Wiley Periodicals, Inc. Complexity 21: 259-267, 2016 [ABSTRACT FROM AUTHOR]

The effect of high-density polyethylene (HDPE) on the textural features of experimental coke was investigated using polarized-light optical microscopy and wavelet-based image analysis. Metallurgical coke samples were prepared in a laboratory-scale furnace with 2.5%, 5.0%, 7.5%, 10.0%, and 12.5% HDPE by mass, and one sample was prepared by 100% coal. The amounts and distribution of textures (isotropic, mosaic and banded) and pores were obtained. The calculations reveal that the addition of HDPE results in a decrease of mosaic texture and an increase of isotropic texture. Ethylene formed from the decomposition of HDPE is considered as a probable reason for the texture modifications. The approach used in this study can be applied to indirect evaluation for the reactivity and strength of coke. [ABSTRACT FROM AUTHOR]

The strength of coke is of major importance for efficient blast furnace operation. There are only a few studies related to compressive coke hot strength, possibly due to experimental difficulties. In this work, it has been demonstrated that the Gleeble thermomechanical simulator is suitable for evaluating coke hot strength and offers many benefits compared to purpose-built devices reported in the literature. This finding could open coke hot strength research to a wider number of scientists. The compressive hot strength of coke was evaluated at 1000 and 1600°C by testing 50 samples at both temperatures. The yield strength and ultimate strength of the coke were, respectively, 46 and 20% lower at 1600°C than 1000°C. Stress-strain curves showed that the coke was brittle at 1000°C but partially plastic at 1600°C. The significantly lower coke strength at 1600°C could help explain the smaller coke lump size found near the tuyere level in quenched blast furnaces. [ABSTRACT FROM AUTHOR]

The article presents a study which evaluates the possible production of mono-, di- and hemicalcium ferrite phases via melt for reduction kinetics investigations. Scanning electron microscopy (SEM-EDS) and x-ray diffraction (XRD) were used to identify mineral compositions of calcium ferrite samples. Results of the study indicate the possible production of the samples of calcium ferrites via melting, in which thermodynamic calculations were used to estimate conditions needed for calcium ferrites.

Conceptual change theories assume that knowledge structures grow during the learning process but also get reorganized. Yet, this reorganization process itself is hard to examine. By using concept maps, we examined the changes in students' knowledge structures and linked it to conceptual change theory. In a longitudinal study, thirty high-achieving students (M = 14.41 years) drew concept maps at three timepoints across a teaching unit on magnetism and electrostatics. In total, 87 concept maps were analyzed using betweenness and PageRank centrality as well as a clustering algorithm. We also compared the students' concept maps to four expert maps on the topic. Besides a growth of the knowledge network, the results indicated a reorganization, with first a fragmentation during the unit, followed by an integration of knowledge at the end of the unit. Thus, our analysis revealed that the process of conceptual change on this topic was non-linear. Moreover, the terms used in the concept maps varied in their centrality, with more abstract terms being more central and thus more important for the structure of the map. We also suggest ideas for the usage of concept maps in class. [ABSTRACT FROM AUTHOR]