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The paradox of the tight spiral pass in American football: A simple resolution
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| Pengarang | : | Richard H. Price |
| Nama Majalah/Jurnal | : | American Journal of Physics |
| Volume / Edisi | : | 88 (No. 9) |
| Halaman | : | 704-710 |
| Abstrak | : | An American football is a rotationally symmetric object, which, when well-thrown, spins rapidly around its symmetry axis. In the absence of aerodynamic effects, the football would be a torque-free gyroscope and the symmetry/spin axis would remain pointing in a fixed direction in space as the football moved on its parabolic path. When a pass is well-thrown through the atmosphere, however, the symmetry axis remains—at least approximately—tangent to the path of motion. The rotation of the symmetry axis must be due to aerodynamic torque; yet, that torque, at first glance, would seem to have precisely the opposite effect. Here, we explain the action of aerodynamics on the ball's orientation at second glance. |
Electromagnetic radiation and the self-field of a spherical dipole oscillator
| Pengarang | : | Masud Mansuripur |
| Nama Majalah/Jurnal | : | American Journal of Physics |
| Volume / Edisi | : | 88 (No. 9) |
| Halaman | : | 693-703 |
| Abstrak | : | For an oscillating electric dipole in the shape of a small, solid, uniformly polarized, spherical particle, we compute the self-field as well as the radiated electromagnetic field in the surrounding free space. The assumed geometry enables us to obtain the exact solution of Maxwell's equations as a function of the dipole moment, the sphere radius, and the oscillation frequency. The self-field, which is responsible for the radiation resistance, does not introduce acausal or otherwise anomalous behavior into the dynamics of the bound electrical charges that comprise the dipole. Departure from causality, a well-known feature of the dynamical response of a charged particle to an externally applied force, is shown to arise when the charge is examined in isolation, namely, in the absence of the restraining force of an equal but opposite charge that is inevitably present in a dipole radiator. Even in this case, the acausal behavior of the (free) charged particle appears to be rooted in the approximations used to arrive at an estimate of the self-force. When the exact expression of the self-force is used, our numerical analysis indicates that the impulse response of the particle should remain causal. |
The Scientific Curiosity of Preservice Elementary Teachers and Confidence for Teaching Specific Science Topics
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Journal of Science Teacher Education |
| Volume / Edisi | : | 34 (No. 7-8) |
| Halaman | : | 883-902 |
| Abstrak | : | This study explored whether, and how, preservice elementary tea chers’ scientific curiosity related to their confidence for science teach ing. A group of 29 preservice, elementary teachers in the U.S. engaged in a curiosity journaling strategy across a 16-week scientific inquiry course. Their expressions of curiosity were coded using Luce and Hsi’s framework of curiosity. Whether expressions of curiosity related to their confidence for teaching associated science topics was examined statistically. In addition, the categories of their curiosity were coded and are described across eight journal entries. The nature of the relationship between scientific curiosity and science teaching confi dence, as well as the nature of the curiosity they expressed, are described. Generally, curiosity about specific scientific phenomena and changes in confidence for teaching those topics did not relate to one another. Relationships did emerge, however, among categories of curiosity and participants’ confidence for teaching seven specific science topics. |
How Teachers' Knowledge of Curriculum Supports Partnering with Students in Their Science Learning
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Journal of Science Teacher Education |
| Volume / Edisi | : | 34 (No. 7-8) |
| Halaman | : | 861-882 |
| Abstrak | : | A key goal of science learning today is to support students in posing and answering questions about phenomena that matter to them while establishing a need to grapple with disciplinary ideas and practices reflected in standards. To be successful in this endeavor, teachers need to learn to partner with students on the direction of their learning while remaining attentive to goals for learning reflected in standards. In this paper, we explore the idea that educators' developing knowl edge of curricular purposes and structures can help support their enactment of instructional materials that help them balance these two goals. Our study draws on 36 teachers' experiences of learning to teach with instructional materials aligned to the Next Generation Science Standards as part of a field test that included multiple cycles of professional development workshops and enactments. Our findings illustrate how teachers' knowledge of curriculum can help them make sense of their own growth in teaching. |
University Teachers’ Experiences of Teaching Hands-On Components in Science and Technology in Primary Teacher Education during COVID-19
| Pengarang | : | Hallström, Jonas,Frejd, Johanna |
| Nama Majalah/Jurnal | : | Journal of Science Teacher Education |
| Volume / Edisi | : | 34 (No. 7-8) |
| Halaman | : | 841-860 |
| Abstrak | : | Teacher education programs have the dual task of teaching specific subject content while also providing examples of how this content can be taught in schools. This task is especially important, and also proble matic, when it comes to technology and science education, where hands-on components such as design/construction exercises, labora tory exercises, and excursions are central epistemic practices. When COVID-19 hit, Swedish universities were forced to change from cam pus-based teaching to online distance education, termed “emergency remote teaching (ERT).” The present study aims to investigate univer sity teachers’ experiences of how hands-on components in science and technology education worked in the ERT mode that arose during the COVID-19 pandemic. The analysis was performed with a social semiotics and community of inquiry framework, and shows that both the type of instruction and the subject content were impacted. In particular, the reduced opportunities for students to apply scientific and technical methods and the reduced ability of teachers to deter mine whether the students had understood their instruction gener ated new ways of communicating and supporting the students’ learning. Therefore, analysis of meaning making in science and tech nology online-learning contexts needs to address the topics of the nature of science (NOS) and the nature of technology (NOT). An extended, three-dimensional model of meaning making is suggested. |
Structure of numerical algorithms and advanced mechanics
| Pengarang | : | Siu A. Chin |
| Nama Majalah/Jurnal | : | American Journal of Physics |
| Volume / Edisi | : | 88 (No. 10) |
| Halaman | : | 883-894 |
| Abstrak | : | Most elementary numerical schemes found useful for solving classical trajectory problems are canonical transformations. This fact should be made more widely known among teachers of computational physics and Hamiltonian mechanics. From the perspective of advanced mechanics, unlike that of numerical schemes, there are no bewildering number of seemingly arbitrary elementary schemes based on Taylor's expansion. There are only two canonical first and second order algorithms, on the basis of which one can comprehend the structures of higher order symplectic and non-symplectic schemes. This work shows that most elementary algorithms up to the fourth-order can be derived from canonical transformations and Poisson brackets of advanced mechanics. |
Investigating the Quality of Enacted Pedagogical Content Knowledge by Mapping Out Component Interactions: A Case Study of a Teacher Educator Teaching Basic Genetics
| Pengarang | : | Buma, Anastasia,Nyamupangedengu, Eunice |
| Nama Majalah/Jurnal | : | Journal of Science Teacher Education |
| Volume / Edisi | : | 34 (No. 7-8) |
| Halaman | : | 820-840 |
| Abstrak | : | The teaching of genetics has not been effective in promoting a scientifically acceptable understanding of basic genetics concepts. This study addresses that gap by reporting on topic-specific pedagogi cal content knowledge (PCK) enacted by a teacher educator as she teaches a content course on basic genetics concepts to fourth-year pre service teachers. A qualitative case study was conducted to investigate the nature of manifested content specific component interactions and the possible value in enhancing the learning of basic genetics concepts. This study is rooted in the refined consensus model of PCK with a focus on the enacted PCK (ePCK). The PCK framework informed the under standing of the ePCK components in this study as well as the design of an ePCK rubric and other qualitative analysis enablers. They were used in this study to analyze the data captured through written Content Representations (CoRes), video-recorded lectures, and interviews over a 3-year period. The findings indicate that the ePCK manifested in planning and teaching was reasoned pedagogically and of high quality and more so, perceived to enhance students' learning. By year three, revealed ePCK consisted mostly of proficient and sophisticated ePCK with coherent component interactions that are indicative of enriched explanations and learning tasks such as the sequencing of the concepts, well-thought-out instructional representations, and learner prior knowl edge. Therefore, the generated insights are strong evidence about the kind of teaching that can significantly address misconceptions and what makes genetics concepts dif f icult to learn- a knowledge that should be significant to others in the field. |
Visualizing topological transport
| Pengarang | : | Mariya A. Lizunova |
| Nama Majalah/Jurnal | : | American Journal of Physics |
| Volume / Edisi | : | 88 (No. 10) |
| Halaman | : | 876-882 |
| Abstrak | : | We present a mathematically simple procedure for explaining and visualizing the dynamics of quantized transport in topological insulators. The procedure serves to illustrate and clarify the dynamics of topological transport in general, but for the sake of concreteness, it is phrased here in terms of electron transport in a charge-ordered chain, which may be mapped exactly onto transport between edge channels in the Integer Quantum Hall Effect. This approach has the advantage that it allows a direct visualization of the real-space and real-time evolution of the electronic charges throughout the topological pumping cycle, thus demystifying how charge flows between remote edges separated by an insulating bulk, why the amount of transported charge is given by a topological invariant, and how continuous driving yields a discrete, quantized amount of transported charge. |
Comment on “The equivalence principle in the Schwarzschild geometry” [Am. J. Phys. 62, 1037 (1994)]
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | American Journal of Physics |
| Volume / Edisi | : | 88 (No. 10) |
| Halaman | : | 874-875 |
| Abstrak | : | In the article “The equivalence principle in the Schwarzschild geometry” [Am. J. Phys. 62, 1037–1040 (1994)], some manifestation of the equivalence principle in Schwarzschild spacetime was studied. We point out that the result for the Riemann-tensor component in this article is incorrect because only the first order terms in the metric expansion are taken into account. We show the corrected result, illustrating the importance of the second order terms in the approximate metric in computing curvature quantities. |
Teacher Noticing for Supporting Students' Epistemic Agency in Science Sensemaking Discussions
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Journal of Science Teacher Education |
| Volume / Edisi | : | 34 (No. 7-8) |
| Halaman | : | 799-819 |
| Abstrak | : | Calls to immerse students in the sensemaking practices of science recommend that students propose ideas and work together to con struct explanations as well as drive the evaluation and decision-making around classroom knowledge-building. In other words, they should be participating with epistemic agency. Part of the teaching work of sup porting student sensemaking, therefore, is to intentionally open up space for student contributions and negotiations during sensemaking. The type of space that is opened up for students' sensemaking is highly dependent on teachers' choices and interpretations of student contri butions. Accordingly, this paper leverages a teacher noticing framework to begin to characterize the teacher noticing and decision-making involved in supporting students' epistemic agency while teaching. Using a novel point-of-view video collection methodology, we asked two teachers to identify moments while teaching in which they were making a decision about how to open up or close down space for students' epistemic agency. We found that both teachers attended similarly to the disciplinary substance of students' ideas; the epistemic nature of students' ideas; students' epistemic stance or orientation during participation; and students' overall degree of engagement. Teachers' responses to students varied across pedagogical phenomena, and they also varied in their effectiveness. These variations were related to each teacher's conception of epistemic agency. We propose that atten tion to the epistemic nature of students' responses and to students' epistemic stance or orientation may be especially important foci of teacher attention for supporting students' epistemic agency. |