South African physical sciences teachers’ perceptions of new content in a revised curriculum

This paper reports on South African teachers’ perceptions of the educational value of new topics in a revised physical sciences high school curriculum, their content knowledge competency of these topics, and their pedagogical content knowledge in teaching them. In view of the historical inequalities of the South African education system, a focus of the study was comparison of these perceptions of teachers based at schools which are diverse in terms of location, student population, and availability of resources. We adopted a mixed methods approach in collecting and analysing data from a large-scale survey of teachers through a structured questionnaire, and followed this with interviews with 10 teachers in seeking more in-depth explanations of the findings. The study revealed that teachers at township and rural schools previously designated for black students, and suburban and city schools previously reserved for white students, have a positive perception of the new topics introduced into the revised curriculum. However, teachers at all these schools expressed uncertainly as to their content knowledge and pedagogical knowledge of the new topics.Keywords: content knowledge; pedagogical content knowledge; pedagogical knowledg

Revisiting the Roles of Legal Rules and Tax Rules in Income Redistribution: A Response to Kaplow & Shavell

The debate over whether legal rules should be used to redistribute resources in society or whether redistribution should be left exclusively to the tax-and-transfer system has long occupied philosophers, political theorists, economists, and legal academicians. For many years, the conventional wisdom on this question among legal scholars seemed to be that blanket generalizations were inappropriate. All systems of redistribution distort individuals\u27 choices and entail administrative costs. Therefore, the argument went, a universal preference for using the tax-and-transfer system to redistribute is not justified. Rather, the choice among institutions to accomplish society\u27s redistributive goals was considered to be an empirical one which must be resolved on a case-by-case basis, in the light of detailed information about the circumstances likely to influence the effectiveness of each method of redistribution. At some point, however, a contrary view developed among economists, a view that has become the new conventional wisdom: that income (or wealth) redistribution is always better accomplished through the tax-andtransfer system than through the legal system. One of the arguments traditionally offered to support this view is that redistribution through the legal system is by nature more haphazard (in the sense of less comprehensive and less precise) than redistribution through the tax system. That is, the tax system can redistribute from all better-off to all worse-off individuals, whereas the legal system can redistribute only from those better off to those worse off who are subject to the legal rule in question. In addition, it was often argued that the legal system\u27s capacity for income redistribution is, in any event, small because redistributive legal rules will be effective only in settings in which the parties are not able to contract around the redistributive effect of those rules. Thus, the argument goes, legal rules can perform a meaningful redistributive function only in situations involving non-contract-based rules, such as tort rules governing the conduct of strangers ( that is, individuals not in a contractual relationship with one another). In general, with some significant qualifications, we agree that the haphazardness and contracting-around arguments provide a basis for generally preferring the tax-and-transfer system as the primary means of reducing income inequality

Revisiting the Roles of Legal Rules and Tax Rules in Income Redistribution: A Response to Kaplow & Shavell

The debate over whether legal rules should be used to redistribute resources in society or whether redistribution should be left exclusively to the tax-and-transfer system has long occupied philosophers, political theorists, economists, and legal academicians. For many years, the conventional wisdom on this question among legal scholars seemed to be that blanket generalizations were inappropriate. All systems of redistribution distort individuals\u27 choices and entail administrative costs. Therefore, the argument went, a universal preference for using the tax-and-transfer system to redistribute is not justified. Rather, the choice among institutions to accomplish society\u27s redistributive goals was considered to be an empirical one which must be resolved on a case-by-case basis, in the light of detailed information about the circumstances likely to influence the effectiveness of each method of redistribution. At some point, however, a contrary view developed among economists, a view that has become the new conventional wisdom: that income (or wealth) redistribution is always better accomplished through the tax-andtransfer system than through the legal system. One of the arguments traditionally offered to support this view is that redistribution through the legal system is by nature more haphazard (in the sense of less comprehensive and less precise) than redistribution through the tax system. That is, the tax system can redistribute from all better-off to all worse-off individuals, whereas the legal system can redistribute only from those better off to those worse off who are subject to the legal rule in question. In addition, it was often argued that the legal system\u27s capacity for income redistribution is, in any event, small because redistributive legal rules will be effective only in settings in which the parties are not able to contract around the redistributive effect of those rules. Thus, the argument goes, legal rules can perform a meaningful redistributive function only in situations involving non-contract-based rules, such as tort rules governing the conduct of strangers ( that is, individuals not in a contractual relationship with one another). In general, with some significant qualifications, we agree that the haphazardness and contracting-around arguments provide a basis for generally preferring the tax-and-transfer system as the primary means of reducing income inequality

Transforming energy instruction in middle school to support integrated understanding and future learning

Energy is a fundamental unifying concept of science, yet common approaches to energy instruction in middle school have shown little success with helping students develop their naïve ideas about energy into more sophisticated understandings that are useful for making sense of their experiences. While traditional energy instruction often focuses on simple calculations of energy in idealized systems, we developed a new middle school energy unit that focuses qualitatively on the energy transformations that occur in everyday, nonidealized, systems. In this article, we describe our approach to energy instruction and report the effects this approach had on students' energy conceptions, ability to perform on distal criterion‐referenced assessments, and preparation for future energy‐related learning. Results indicate that during instruction, students' energy conceptions progress from a set of disconnected ideas toward an integrated understanding that is organized around the principle of transformation, and that these more integrated conceptions both boost students' ability to make sense of everyday phenomena and lay the groundwork for more efficient and meaningful energy‐related learning in the future. © 2010 Wiley Periodicals, Inc. Sci Ed 95: 670–699, 2011Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87139/1/20423_ftp.pd

On trend analysis in climatic time series, with application to surface temperature

The deletion of a trend as an initial step in the analysis of climatic time series may result in the elimination of low-frequency components which constitute an integral part of climatic variability. An example is given here showing that linear trend deletion from the time series of the World Ocean annual sea-surface temperature (1850–2009) reduces the low-frequency (from 0.02 year–1 to 0.001 year–1) part of the time series spectrum by ∼40% to 80% thus severely distorting the spectrum of climate. As an additional result, it is shown that the current warming can be explained in full within the framework of a stationary stochastic model fitted directly to the time series of annual sea-surface temperature (SST) from 1850 through 2009 with no trend deletion. According to the model, the recurrence time of runs of generally increasing temperature by ∼0.5°C lasting for several decades (as has been observed since about 1956) is about 500 years for the World Ocean. Thus, the current run of growing SST is not an extremely rare event in climate and can be explained as a part of the natural climatic variability. These results show that deleting linear trends requires a thorough preliminary analysis. It is suggested that the approach described here can be used to improve physical models of the World Ocean climate

Middle school students' use of the energy concept to engage in new learning: What ideas matter?

One reason for the widespread use of the energy concept across the sciences is that energy analysis can be used to interpret the behavior of systems even if one does not know the particular mechanisms that underlie the observed behavior. By providing an approach to interpreting unfamiliar phenomena, energy provides a lens on phenomena that can set the stage for deeper learning about how and why phenomena occur. However, not all energy ideas are equally productive in setting the stage for new learning. In particular, researchers have debated the value of teaching students to interpret phenomena in terms of energy forms and transformations. In this study, we investigated how two different approaches to middle school energy instruction—one emphasizing energy transformations between forms and one emphasizing energy transfers between systems—prepared students to use their existing energy knowledge to engage in new learning about a novel energy-related phenomenon. To do this, we designed a new assessment instrument to elicit student initial ideas about the phenomenon and to compare how effectively students from each approach learned from authentic learning resources. Our results indicate that students who learned to interpret phenomenon in terms of energy transfers between systems learned more effectively from available learning resources than did students who learned to interpret phenomena in terms of energy forms and transformations. This study informs the design of introductory energy instruction and approaches for assessing how students existing knowledge guides new learning about phenomena

Collaborative Design Work in Technology Education

Peer reviewe

‘Even though it might take me a while, in the end, I understand it’: a longitudinal case study of interactions between a conceptual change strategy and student motivation, interest and confidence

Although there have been many investigations of the social, motivational, and emotional aspects of conceptual change, there have been few studies investigating the intersection of these factors with cognitive aspects in the regular classroom. Using a conceptual change approach, this case study reports experiences of a student of low to average prior attainment who achieved high levels of conceptual gains in five science topics over a two-year period. Her experience in the cognitive, social and affective domains was probed through analysis of interviews, student artefacts, video recordings of classroom learning, pre/post-tests and questionnaire results. For this student, peripheral or incidental persuasion of belonging to a supportive small group initially led to greater engagement with the construction of understanding through production of multiple student-generated representations, resulting in improved self-confidence and high levels of conceptual change. Evidence of transfer from performance to mastery approach goals, adoption of positive activating emotions and increased interest in science were observed. This study highlights that adoption of a multidimensional conceptual change approach with judicious organisation of small groups to support construction of verbal, pictorial and written representations of understanding may bring about changes in motivational stance, self-confidence and emotions to maximise conceptual change