Forces and Motion: How Young Children Understand Causal Events

How do children evaluate complex causal events? This study investigates preschoolers' representation of force dynamics in causal scenes, asking whether (a) children understand how single and dual forces impact an object's movement and (b) this understanding varies across cause types (Cause, Enable, Prevent). Three‐and‐a half‐ to 5.5‐year‐olds (n = 60) played a board game in which they were asked to predict the endpoint of a ball being acted upon by one or two forces. Children mostly understood the interactions of forces underlying each type of cause; only 5.5‐year‐olds could integrate two contradictory forces. Children perceive force interactions underlying causal events, but some concepts might not be fully understood until later in childhood. This study provides a new way of thinking about causal relations.     

Well-founded social fictions: a defence of the concepts of institutional and familial habitus

This article engages with Atkinson’s recent criticisms of concepts of collective habitus, such as ‘institutional’ and ‘familial’ habitus, in order to defend their conceptual utility and theoretical coherence. In so doing we promote a flexible understanding of habitus as both an individual and a collective concept. By retaining this flexibility (which we argue is in keeping with the spirit of Bourdieuian philosophy) we allow for a consideration of the ways in which the individual habitus relates to the collective. We argue that, through recognition of the complexity of the interrelated habitus of individuals, collective notions go beyond individualist accounts that perceive only the relational aspects of the individual with the social field. Our approach allows us to consider social actors in relation to each other and as constitutive of fields rather than as mere individuals plotted in social space. These arguments will be woven through our responses to what Atkinson calls the three fatal flaws of institutional and familial habitus: namely, homogenisation, anthropomorphism, and substantialism.     

Variables affecting physics achievement

Much research has focused on student views about physics concepts, with an emphasis on the identification of alternative conceptions, and how curricula and professional development may ameliorate the situation. However, there has been little work on determining the extent of, and in separating, the student and teacher/classroom level variables that may impact student physics achievement. This study examined the effect of different student and teacher/classroom level variables on student understanding of physics concepts using hierarchical linear modeling (HLM), a regression based technique. The data were collected from 68 different teachers and 3,119 students who were using a reform curriculum, Active Physics. Teachers and students completed surveys asking about their beliefs, their classes and their personal characteristics. Students also completed a physics achievement test. The data show that students of teachers who used Active Physics for a greater portion of the year scored higher on the achievement test than did students of teachers who did not use the curriculum as much. Furthermore, the data show that the achievement gap was narrowed between boys and girls and between students with different attitudes toward physics. Additionally teachers who received inservice instruction on how to implement Active Physics narrowed the gap between students with different views of their classroom involvement. © 2009 Wiley Periodicals, Inc. J Res Sci Teach 46: 961–976, 2009     

Assessing perceived need support and need satisfaction in physical education: adaptation and validation with English students

This study aimed to validate an English version of Basic Psychological Needs Support Questionnaire (BPNSQ) and the Basic Psychological Needs in Physical Education Scale (BPN-PE) in the physical education context. Participants included 453 students aged between 12 and 17 years. For the BPNSQ, the hypothesized three-factor solution displayed high interfactor correlations (rs > 1), and a follow-up analysis indicated that the items were represented by a single need-support factor. For the BPN-PE, hypothesized three-factor solution was supported. Both scales were found invariant across gender, and the nomological validity was also demonstrated through the associations between factors of both scales. This study provides initial support for the use of the BPN-PE to assess psychological need satisfaction within the physical education context among English-speaking adolescents. The hypothesized three-factor structure of the BPNSQ was not supported and more research is needed to evaluate the English version in the physical education context.     

Single view silhouette fitting techniques for estimating tennis racket position

Stereo camera systems have been used to track markers attached to a racket, allowing its position to be obtained in three-dimensional (3D) space. Typically, markers are manually selected on the image plane, but this can be time-consuming. A markerless system based on one stationary camera estimating 3D racket position data is desirable for research and play. The markerless method presented in this paper relies on a set of racket silhouette views in a common reference frame captured with a calibrated camera and a silhouette of a racket captured with a camera whose relative pose is outside the common reference frame. The aim of this paper is to provide validation of these single view fitting techniques to estimate the pose of a tennis racket. This includes the development of a calibration method to provide the relative pose of a stationary camera with respect to a racket. Mean static racket position was reconstructed to within ±2 mm. Computer generated camera poses and silhouette views of a full size racket model were used to demonstrate the potential of the method to estimate 3D racket position during a simplified serve scenario. From a camera distance of 14 m, 3D racket position was estimated providing a spatial accuracy of 1.9 ± 0.14 mm, similar to recent 3D video marker tracking studies of tennis.     

Physiological implications of preparing for a natural male bodybuilding competition

This study aimed to describe the body composition and physiological changes which take place during the in-season and recovery periods of a group of natural bodybuilders. Natural male bodybuilders (n?=?9) were assessed 16 (PRE16), 8 (PRE8), and 1 (PRE1) week(s) before, and 4 (POST4) weeks after a bodybuilding competition. Assessments included body composition, resting metabolic rate (RMR), serum hormones, and 7-day weighed food and training diaries. Change in parameters was assessed using repeated-measures analysis of variance. Dietary protein intake remained high throughout the study period (2.8–3.1?g?kg^?1?d^?1). Fat mass (FM) was significantly reduced from PRE16 to PRE1 (8.8?±?3.1 vs. 5.3?±?2.4?kg, P?.01). There was a small decrease in lean mass (LM) from PRE8 to PRE1 (71.8?±?9.1 vs. 70.9?±?9.1?kg, P?P?>?.05). Large reductions in total and free testosterone (16.4?±?4.4 vs. 10.1?±?3.6?nmol?L^?1, P?. 116.8?±?76.9?pmol?L^?1, P?. 19.9?±?7.6?nmol?L^?1, P?. 72.5?±?8.5?kg, P?. 25.4?±?9.3?nmol?L^?1, P?相似文献   

Determining the ROI of an online English as a second language program

This article examines the methodology used to determine the return on investment (ROI) of an online English as a Second Language (ESL) program. The online ESL program was implemented in over 20 countries, and the scope of the analysis includes data from all participating countries. A form of ROI analysis had been conducted annually prior to the addition of the Phillips methodology in 2008. The latest analysis follows the Phillips approach step by step and has provided greater credibility as a result.     

Observing the coach-created motivational environment across training and competition in youth sport

Adopting an integrated achievement goal (Nicholls, J. G. (1989). The competitive ethos and democratic education. Cambridge, MA: Harvard University Press.) and self-determination theory (Deci, E. L., & Ryan, R. M. (2000). The “what” and “why” of goal pursuits: Human needs and the self-determination of behavior. Psychological Inquiry, 11, 227–268. doi:10.1207/S15327965PLI1104_01) perspective as proffered by Duda, J. L. (2013). (The conceptual and empirical foundations of empowering coaching^TM: Setting the stage for the PAPA project. International Journal of Sport and Exercise Psychology, 11, 311–318. doi:10.1080/1612197X.2013.839414), the aim of the current study was to observe empowering and disempowering features of the multidimensional motivational coaching environment in training and competition in youth sport. Seventeen grass-roots soccer coaches were observed and rated in training and competitive settings using the multidimensional motivational climate observation system (MMCOS; Smith, N., Tessier, D., Tzioumakis, Y., Quested, E., Appleton, P., Sarrazin, P., … Duda, J. L. (2015). Development and validation of the multidimensional motivational climate observation system (MMCOS). Journal of Sport and Exercise Psychology, 37, 4–22. doi:10.1123/jsep.2014-0059). In line with our hypotheses, coaches created different motivational environments in the two contexts. More specifically, coaches were observed to create a less empowering and more disempowering environment in competition compared to in training. The observed differences were underpinned by distinctive motivational strategies used by coaches in the two contexts. Findings have implications for the assessment of the coach-created motivational environment and the promotion of quality motivation for young athletes taking part in grass-roots-level sport.