Students' understandings of logical implication

We report results from an analysis of responses to a written question in which high-attaining students in English schools, who formed part of a longitudinal nation-wide survey on proof conceptions, were asked to assess the equivalence of two statements about elementary number theory, one a logical implication and the other its converse, to evaluate the truth of the statements and to justify their conclusions. We present an overview of responses at the end of Year 8 (age 13 years) and an analysis of the approaches taken, and follow this with an analysis of the data collected from students who answered the question again in Year 9 (age 14 years) in order to distinguish learning trajectories. From these analyses, we distinguished three strategies, empirical, focussed-empirical and focussed-deductive, that represent shifts in attention from an inductive to a deductive approach. We noted some progress from Year 8 to Year 9 in the use of the focussed strategies but this was modest at best. The most marked progress was in recognition of the logical necessity of a conclusion of an implication when the antecedent was assumed to be true. Finally we present some theoretical categories to capture different types of meanings students assign to logical implication and the rationale underpinning these meanings. The categories distinguish responses where a statement of logical implication is (or is not)interpreted as equivalent to its converse, where the antecedent and consequent are (or are not) seen as interchangeable, and where conclusions are (or are not)influenced by specific data. This revised version was published online in July 2006 with corrections to the Cover Date.     

Students' understandings about animal skeletons

Surprisingly few studies have looked at people's understanding of skeletons. Most of the work in this field that has been done has only involved children's understanding of human skeletons. This study looks at students' understandings of the structure of animal (including human) skeletons. A crosssectional approach was used involving a total of 175 students in England from six different age groups (ranging from 4 year olds to 20 year olds). Students were presented, on separate occasions, with specimens of a brown rat, a starling and a herring and asked to draw what they thought was inside each specimen. On a final occasion, they were also asked to draw what they thought was inside themselves. Repeated inspections of the completed drawings allowed us to construct a seven point scale of 'skeletal understanding'. Our analysis shows the extent to which student understanding increases with age and the degree to which pupils know more about human than other skeletons. The findings are interpreted with reference to current trends in English science curricula and pedagogy. We comment in particular on the current inability of most students to see the skeleton as a functional, integrated whole.     

Reasoning across ontologically distinct levels: Students' understandings of molecular genetics

In this article we apply a novel analytical framework to explore students' difficulties in understanding molecular genetics—a domain that is particularly challenging to learn. Our analytical framework posits that reasoning in molecular genetics entails mapping across ontologically distinct levels—an information level containing the genetic information, and a physical level containing hierarchically organized biophysical entities such as proteins, cells, tissues, etc. This mapping requires an understanding of what the genetic information specifies, and how the physical entities in the system mediate the effects of this information. We therefore examined, through interview and written assessments, 10th grade students' understandings of molecular genetics phenomena to uncover the conceptual obstacles involved in reasoning across these ontologically distinct levels. We found that students' described the genetic instructions as containing information about both the structure and function of biological entities across multiple organization levels; a view that is far less constrained than the scientific understandings of the genetic information. In addition, students were often unaware of the different functions of proteins, their relationship to genes, and the role proteins have in mediating the effects of the genetic information. Students' ideas about genes and proteins hindered their ability to reason across the ontologically distinct levels of genetic phenomena, and to provide causal mechanistic explanations of how the genetic information brings about effects of a physical nature. © 2007 Wiley Periodicals, Inc. J Res Sci Teach 44: 938–959, 2007     

Students' conceptions of chemical change

One hundred high school chemistry students who had completed a unit on chemical change were given a written instrument in which they were shown three oxidation-reduction reactions and were asked to explain them. Eleven students representing a range of achievement levels were chosen for more intensive clinical interviews in which they explained their responses, evaluated the quality of their responses, and compared them to other hypothetical responses. Interview results revealed that students commonly experienced difficulties at three different epistemological levels: 1. Chemical knowledge. Most students failed to invoke atoms and molecules as explanatory constructs, even though they had been emphasized in their chemistry course. Some students also listed “substances” such as heat, cold, or decay as reactants or products. 2. Conservation reasoning. Many students could not predict or explain mass changes in the chemical reactions. Their most common problems included (a) a tendency to treat chemical changes such as rusting as physical changes in form or state, and (b) failure to understand the role of invisible (in this case gaseous) reactants or products in the reactions. 3. Explanatory ideals. Many students demonstrated a preference for explanations based on superficial analogies with everyday events (e.g., rusting is like decay) over explanations based on chemical theories. Only one of the 11 students interviewed demonstrated mastery of the unit's contents at all three levels. Results of this and other research indicate a need for substantial revision in chemistry teaching practice.     

Students' and teachers' explanations of chemical equilibrium

Specializations: cognitive processes in science learning and teaching.     

化学反应快慢与限度

[题目]在化工生产中,反应物如能多快好省地尽可能转变成人们需要的生成物.将对人类合理利用自然资源,为生产、生活和科研服务,具有十分重要的意义.     

Metaphorical understandings and scientific ideas

This study looks at the ideas which children have of the particulate model of matter, at the time they start formal science in school. Pupils aged about eleven in three European countries‐‐Greece, Portugal and the UK‐‐were studied using word association tests. In the UK and Portugal the children had received no teaching of the particulate model; in Greece the pupils had received one year of introductory science, containing some teaching of the particulate model. Key words associated with the particulate model were investigated as free associations. In Portugal and the UK there was little or no evidence of particulate ideas in the pupils’ responses. In the Greek data particulate ideas were more in evidence. There were other clear differences in the data from the three countries. Educational and research implications of the findings are discussed.     

Classification of chemical reactions: Stages of expertise

In this study we explore the strategies that undergraduate and graduate chemistry students use when engaged in classification tasks involving symbolic and microscopic (particulate) representations of different chemical reactions. We were specifically interested in characterizing the basic features to which students pay attention when classifying chemical reactions at the symbolic and microscopic levels. We identified the categories that students create when classifying chemical reactions, and compared the performance in simple classification tasks of students with different levels of preparation in the discipline. Our results suggest that advanced levels of expertise in chemical classification do not necessarily evolve in a linear and continuous way with academic training; a significant proportion of undergraduate students, regardless of their level of preparation in chemistry, based their classification schemes on the identification of surface features and failed to create chemically meaningful classes. Students' ability to identify chemically meaningful groups was strongly influenced by their recent learning experiences and their graduate work in chemistry. The level of expertise and the type of chemical representation influenced the number and types of categories created, the nature of the features used to build a class, and the role that these features played during the classification process. Although all of the participants in our study expressed similar levels of unfamiliarity with the microscopic images of chemical reactions, advanced students were more adept at using the available representational features to build chemical meaning. © 2007 Wiley Periodicals, Inc. J Res Sci Teach 45: 771–793, 2008     

Student understandings of natural selection

This paper examines the continuation of a study investigating senior secondary students' understanding of concepts in biology. In this study, year 11 student understandings of natural selection were examined by questionnaire using different question formats. The SOLO taxonomy of Biggs and Collis (1982) was used as the theoretical framework with which the quality of student learning was assessed. This paper puts forward the usefulness of the SOLO taxonomy in assessing student understanding in biology in general and in examining student understanding of the concept of natural selection in particular. The paper goes on to examine the implications of these results and raises issues which have applicability to criterion-based assessment in secondary science. Specializations: science and technology education, biology teacher education, applications of multimedia to science education     

Students' reasoning about chemical bonding: The lacuna of repulsion

This article concerns a lacuna in chemistry students' reasoning about chemical bonding. Although chemistry students are familiar with the charges that make up the atom––both positive and negative––they refer only to the attraction between unlike charges. Specifically, they ignore the repulsion between the positive nuclei. We named this disregard of repulsion the lacuna of repulsion. Repulsion is a crucial component in the force-based explanation of chemical bonding, presenting the bond as a dynamic equilibrium between attraction and repulsion electrical forces. We noticed this lacuna incidentally while interviewing chemistry students for a bigger project aimed at supporting students in understanding the force-based explanation of chemical bonding. This article describes our systematic qualitative study of the lacuna of repulsion and its impact on mental models of 23 high school chemistry students. Our findings show that students use six mental models, most of them built upon each other. Beginning from a simple mental model that describes the chemical bond as electrons, continuing with the including attraction forces, and completing with repulsion and a dynamic view of the bond. Only when one considers both attraction and repulsion forces and understands the dynamic balance between them is it possible to build the force-based dynamic mental model of chemical bonding.     

Children's understandings of home-school relations

There is a consensus that close home-school links are beneficial for children's education. However, there is a silence about any part that children may play in, and their views on, this process. This paper reports on research in schools with diverse social intakes, looking at children's understandings and experience of home-school relations. Those in inner city schools were far more likely to talk about separation between their home and school lives, as were working class and ethnic minority children generally, as well as older children. However, all the children expressed strong views about the privacy of their home life in relation to schools and teachers.     

Composing new understandings of sustainability in the Anthropocene

The relationship between sustainability and the Anthropocene takes on new meaning in a time of unprecedented human impact on Earth systems. This relationship is at times contested and not well researched but critical in considering how we will respond to environmental challenges of today and the future. Elaborating on the need for new perspectives and nuanced understandings of sustainability, the contributors to this volume draw on posthumanist and “new” feminist materialist methodologies and theoretical lenses to engage readers in ways, which often contrast with prevailing thinking and research. From the cosmopolitics of place in urban Berlin to the watery space of urban wetlands they share research and rich narratives, which illustrate how sustainability is theorized and enacted across a range of diverse educational contexts. Moving beyond the rhetoric of sustainability, the authors invite us to explore innovative ways to engage with new concepts and emerging tensions that are now influencing the fields of education and sustainability.     

Students' and teachers' misapplication of le chatelier's principle: Implications for the teaching of chemical equilibrium

The aim of this article was to study the reasons, strategies, and procedures that both students and teachers use to solve some chemical equilibrium questions and problems. Inappropriate conceptions on teaching and a lack of knowledge regarding the limited usefulness of Le Chatelier's principle, with its vague and ambiguous formulation and textbook presentation, may be some of the sources of misconceptions about the prediction of the effect of changing conditions on chemical equilibrium. To diagnose misconceptions and their possible sources, a written test was developed and administered to 170 1st-year university chemistry students. A chemical equilibrium problem, relating to the students' test, was solved by 40 chemistry teachers. First, we ascertained that teacher's conceptions might influence the problem-solving strategies of the learner. Based on this first aspect, our discussion also concerns students' and teachers' misconceptions related to the Le Chatelier's principle. Misconceptions emerged through: (a) misapplication and misunderstanding of Le Chatelier's principle; (b) use of rote-learning recall and algorithmic procedures; (c) incorrect control of the variables involved; (d) limited use of the chemical equilibrium law; (e) a lack of mastery of chemical equilibrium principles and difficulty in transferring such principles to new situations. To avoid chemical equilibrium misconceptions, a specific pattern of conceptual and methodological change may be considered.     

Students' reactions to teachers' physical attractiveness and nonverbal behavior: Two exploratory studies

Two studies describe how students' reactions are affected by the physical attractiveness and nonverbal behavior of a teacher. In the first experiment, 9- and 13-year-old students watched a videotaped session given by a female teacher. A physical attractiveness stereotype was found in ratings of the teacher; a teacher who looked attractive was rated as more competent and better able to stimulate and motivate students that when she looked unattractive. The second experiment used fifth-grade children who participated individually in a lesson given by a female teacher. Close behaviors by a teacher (eye contact, leaning forward, smiling, and head nods) produced more positive ratings than distant behaviors by the same teacher (little eye contact, leaning away, frowning, and side to side head movements). No effects on academic performance measures were found in either study due to teacher characteristics.     

Towards new understandings of learning disability

Abstract

This article highlights inherent difficulties in defining learning disability, particularly in South Africa. It traces the evolution of the category from ‘minimal brain damage’ through to the more current ‘learners with special educational needs’ and ‘learners with barriers to learning.’ Different definitions or attempts to describe the phenomenon ‘learning disability’ are reviewed. An overview of the current international research in the field is provided with particular reference to research that attempts to define learning disability. Much of this research is framed within the medical model, which has as its foundation positivism and empiricism. This results in research which is deficit-focused; in other words the focus is on pathology. A second reductionist model fragments the phenomenon of learning disability into discrete units, each of which is researched. It is suggested that, in re-thinking learning disability, the focus shifts away from the deficit, pathology based, reductionist focus currently held across disciplines.

The problem inherent in including the notion of ‘discrepancy between potential and performance’ in any definition is discussed, with particular reference to the measurement of ‘potential in South Africa's multicultural and multilingual learner population. The article ends with a proposal that there be a shift in focus to a panoptic view of the child: a view that takes in his strengths and talents. In so doing, the country may be better able to serve this growing population.

With the national shift towards inclusive education, there is a renewed focus on learners euphemistically called learners with special educational needs or the more ‘in vogue’ learners with barriers to learning. Yet what we mean when we bandy these terms about, how well we understand these learners, is questionable. The focus of this article is that sub-group of learners that educators and parents think are just not achieving as they should be achieving, despite themselves, that sub-group we identify as having ‘potential’ but not ‘performance’; that sub-group that we just cannot quite explain, we just cannot quite understand; that sub-group for whom support ranges from placement to pills to punishment!

This article critically evaluates the current understanding of the phenomenon of learning disability as it is understood in the South African context. It begins with an overview of the international research, with particular reference to the notion of definition. Thereafter, it makes comments on the term as it is used in South Africa. In conclusion, the article proposes the need for an alternative understanding of this group of learners.     

音乐创作的造型要素探究

音乐作品是一定社会生活在作曲家头脑中反映的产物 ,生活实践是音乐创作活动中一个根本性的问题 ,是作曲家进行音乐创作的基础。同样 ,作曲家的艺术修养与他的作曲技巧的掌握和提高 ,其基础也是社会生活实践和艺术实践     

Capturing essential understandings of the urban science learning environment

This research is distinctive in that a mixed-methods approach, employing both cogenerative dialogues and student responses from the Constructivist Learning Environment Survey (CLES), was used to help to understand 9th grade urban students?? experiences in their biochemistry class in New York City. Factor analyses of student responses demonstrated that empirically there were four robust scales rather than five. Qualitative analyses, using cogenerative dialogues and informal interviewing, demonstrated that more adaptable forms of teaching, learning and assessing could support a variety of students. Shared with students, the contents of the CLES and cogenerative dialogues created opportunities for understanding ontologies and helped to create, access and appropriate resources that assist in bringing about success in the science classroom.     

灵魂的挣扎与痛苦——对麦克白形象的认识

莎士比亚的戏剧在世界戏剧史上占据着十分重要的地位 ,尤其是他的《麦克白》时至现代越来越引起了人们的关注。一个弑君、残暴的人何以形成如此深刻而凝重的悲剧效果 ?着重从人的愿望、人类的激情给自己带来痛苦与毁灭的角度 ,分析麦克白悲剧的成因 ,可以看出作者围绕着麦克白的行为 ,渐次写出了他思想的变化及变化过程中灵魂的挣扎和痛苦 ,而这一点也正是此剧具有永久艺术魅力的关键所在。