A Multidimensional Assessment of Teachers’ Knowledge of Algebra for Teaching: Developing an Instrument and Supporting Valid Inferences

Numerous researchers have suggested that there are multiple mathematical knowledge and skill areas needed by teachers in order for them to be effective teachers of mathematics: knowledge of the mathematics that are the goals of instruction, advanced mathematics beyond the instructional material, and mathematical knowledge that is specific to what is needed to teach students. The research reported here is about the development of a test of teachers’ knowledge in these three areas related to the teaching of algebra. The test development process is described and the results of several analyses are reported that had the goal of checking whether valid inferences can be made about the hypothesized components of teacher knowledge.     

Motivated Attention and Reward in Parenting

Parenting has a significant and lasting impact on child development. From birth, parents must sensitively and appropriately attend to their infant’s emotional expressions and vocalizations. Accumulating evidence indicates that these infant cues of emotion attract more attention than equivalent adult cues in parents as well as non-parents. We review this evidence and suggest that infant cues hold high incentive value and elicit motivated attention (i.e., enhanced processing of motivationally relevant stimuli), which in turn promotes approach motivation and thus caregiving responses. Further, we discuss data suggesting that infant cues are salient for non-parents, with increasing motivated attention to infant cues in the transition to parenthood. This increase may depend on interactions between the dopamine reward system and the neuropeptide oxytocin. Therefore, we also explore the human and non-human data that support this association and consider potential sources of variability in motivated attention in parents.     

浅析电流互感器饱和对发电厂保护的影响和对策

文章简要地分析了电流互感器产生饱和的原因、特性以及对保护产生的影响,并结合工作经验提出了一些实用的对策,为相关工作人员提供参考。     

A comparison of muscle activations during traditional and abbreviated tennis serves

The abbreviated tennis serve is a relatively novel modification of the traditional serve that has been reported to provide performance advantages over the traditional technique. However, there are limited objective data regarding the benefits and biomechanics of the abbreviated serve; no data exist that describe shoulder muscle activations during the abbreviated serve. The purpose of this study was to compare muscle activations between the traditional and abbreviated serves. Electromyographic data were collected for the anterior and posterior deltoid, infraspinatus, middle trapezius, latissimus dorsi, serratus anterior, and pectoralis major. When muscle activations were compared during each serve phase, no significant differences were observed between the traditional and abbreviated tennis serve techniques, indicating that the traditional and abbreviated serves are similar regarding shoulder muscle activations. These results could have implications for performance of and injury related to the abbreviated versus traditional serve technique. Although the abbreviated serve has anecdotally been described as advantageous, the present data do not indicate any significant advantages or disadvantages in performing the abbreviated serve technique versus the traditional serve.     

Teaching prospective teachers about fractions: historical and pedagogical perspectives

Research shows that students, and sometimes teachers, have trouble with fractions, especially conceiving of fractions as numbers that extend the whole number system. This paper explores how fractions are addressed in undergraduate mathematics courses for prospective elementary teachers (PSTs). In particular, we explore how, and whether, the instructors of these courses address fractions as an extension of the whole number system and fractions as numbers in their classrooms. Using a framework consisting of four approaches to the development of fractions found in history, we analyze fraction lessons videotaped in six mathematics classes for PSTs. Historically, the first two approaches—part–whole and measurement—focus on fractions as parts of wholes rather than numbers, and the last two approaches—division and set theory—formalize fractions as numbers. Our results show that the instructors only implicitly addressed fraction-as-number and the extension of fractions from whole numbers, although most of them mentioned or emphasized these aspects of fractions during interviews.     

Comparison of split double and triple twists in pair figure skating

In this study, we compared the kinematic variables of the split triple twist with those of the split double twist to help coaches and scientists understand these landmark pair skating skills. High-speed video was taken during the pair short and free programmes at the 2002 Salt Lake City Winter Olympics and the 2003 International Skating Union Grand Prix Finals. Three-dimensional analyses of 14 split double twists and 15 split triple twists from eleven pairs were completed. In spite of considerable variability in the performance variables among the pairs, the main difference between the split double twists and split triple twists was an increase in rotational rate. While eight of the eleven pairs relied primarily on an increased rotational rate to complete the split triple twist, three pairs employed a combined strategy of increased rotational rate and increased flight time due predominantly to delayed or lower catches. These results were similar to observations of jumps in singles skating for which the extra rotation is typically due to an increase in rotational velocity; increases in flight time come primarily from delayed landings as opposed to additional height during flight. Combining an increase in flight time and rotational rate may be a good strategy for completing the split triple twist in pair skating.     

基于临床实训中心的SP应用研究分析

本课题组在对临床实训中心的教学功能进行全面分析、研究的基础上，通过使用标准化病人（SP）的对比研究，认为标准化病人（SP）的优点在于可充当不同角色，不但能提供学生查体，有效地与学生进行沟通，而且作为重要评估者，能客观、公正地对学生学习情况进行评价，大大调动了学生学习的积极性。但由于SP缺乏阳性体征，只能作正常体格检查训练。故将临床实训中心模型与SP二者充分结合起来，从正常到异常，从模型到人体，设计不同案例，真假结合，通过训练培养学生的临床思维能力、判断能力以及掌握操作技巧。