The footprint of a tennis ball

The Hawk-Eye line-calling system in tennis uses a footprint of the ball to determine whether the ball was in or out. However, the footprint itself is not measured. It is the ball trajectory through the air that is measured. Measurements of the footprint are presented in this paper, showing how the high initial rate of expansion of the footprint and other technical difficulties can lead to potential errors in the Hawk-Eye system. The footprint was measured for vertical and oblique impacts, and is compared with recent results presented at a tournament where Hawk-Eye was installed.     

Virtual and Physical Experimentation in Inquiry-Based Science Labs: Attitudes, Performance and Access

This study investigated the learning dimensions that occur in physical and virtual inquiry-based lab investigations, in first-year secondary chemistry classes. This study took place over a 2 year period and utilized an experimental crossover design which consisted of two separate trials of laboratory investigation. Assessment data and attitudinal data were gathered and analyzed to measure the instructional value of physical and virtual lab experiences in terms of student performance and attitudes. Test statistics were conducted for differences of means for assessment data. Student attitudes towards virtual experiences in comparison to physical lab experiences were measured using a newly created Virtual and Physical Experimentation Questionnaire (VPEQ). VPEQ was specifically developed for this study, and included new scales of Usefulness of Lab, and Equipment Usability which measured attitudinal dimensions in virtual and physical lab experiences. A factor analysis was conducted for questionnaire data, and reliability of the scales and internal consistency of items within scales were calculated. The new scales were statistically valid and reliable. The instructional value of physical and virtual lab experiences was comparable in terms of student performance. Students showed preference towards the virtual medium in their lab experiences. Students showed positive attitudes towards physical and virtual experiences, and demonstrated a preference towards inquiry-based experiences, physical or virtual. Students found virtual experiences to have higher equipment usability as well as a higher degree of open-endedness. In regards to student access to inquiry-based lab experiences, virtual and online alternatives were viewed favorably by students.     

“Do you see what I see?” Reading a different classroom scene

This paper examines the problem of representing a research site in poststructuralist terms, suggesting that “data” often taken for granted cannot be read to represent “reality” or “truth.” The representation of classroom life produced for analysis is both multifaceted and contradictory. The researcher's positioning within the major discourses governing educational practice may have as much influence on what is seen in the classroom as does the researcher's physical positioning within material reality. Rather than being seen as an impediment to ongoing educational research for change, the findings presented offer a challenge to researchers to make explicit their underlying interests and agendas.     

Health Psychology and Exercise Adherence

The association between vigorous exercise and certain aspects of mental health is well documented. Explanations for this relationship are not well understood, however, and recent developments in sport psychology suggest a renewed interest in health-related topics. Paradoxically, the more fundamental or prerequisite issue of exercise adherence has received little attention from a psychological perspective. Moreover, the research related to adherence has tended ro be atheoretical and unsystematic. The following discussion is designed to reinforce the significance of understanding influences on habitual exercise behavior and to characterize the nature of previous research in this area. An attempt is also made to provide some heuristic advantages which may facilitate future study of the exercise adherence question at both basic and applied levels.     

Universal themes

In this article, the author proposes a model for teaching Art across Key Stages 1 to 3, which takes the concept of ‘Universal Themes’ as its central focus. He welcomes the emphasis on ideas, meanings and communications contained within the new National Curriculum 2000 document for Art & Design. He also describes examples of how schools might develop their teaching of art through this approach in order to re-animate the practical curriculum.     

The Intersection of Language,Education, and Content: Science Instruction for ESL Students

In this study, the author investigated the relationships among Turkish students' perceived computer skills, computer attitudes, quantitative skills, qualitative skills, and gender. The author collected data from a total of 362 undergraduate students. He found that gender was a significant variable to predict computer attitudes but not perceived skills. The author found no significant correlations between perceived computer skills and attitudes. Although computer attitudes and qualitative skills were significantly and negatively correlated, the author found no significant associations between computer skills and quantitative skills and between computer attitudes and quantitative skills. At least one variable explained variances in each of the subscales of the computer-attitude scale.     

String tension effects on tennis ball rebound speed and accuracy during playing conditions

The primary aim of this study was to determine whether variations in rebound speed and accuracy of a tennis ball could be detected during game-simulated conditions when using three rackets strung with three string tensions. Tennis balls were projected from a ball machine towards participants who attempted to stroke the ball cross-court into the opposing singles court. The rebound speed of each impact was measured using a radar gun located behind the baseline of the court. An observer also recorded the number of balls landing in, long, wide and in the net. It was found that rebound speeds for males (110.1?±?10.2?km?·?h^?1; mean?±?s) were slightly higher than those of females (103.6?±?8.6?km?·?h^?1; P?<?0.05) and that low string tensions (180?N) produced greater rebound speeds (108.1?±?9.9?km?·?h^?1) than high string tensions (280?N, 105.3?±?9.6?km?·?h^?1; P?<?0.05). This finding is in line with laboratory results and theoretical predictions of other researchers. With respect to accuracy, the type of error made was significantly influenced by the string tension (P?<?0.05). This was particularly evident when considering whether the ball travelled long or landed in the net. High string tension was more likely to result in a net error, whereas low string tension was more likely to result in the ball travelling long. It was concluded that both gender and the string tension influence the speed and accuracy of the tennis ball.     

Fatigue decreases skilled tennis performance

The aim of this study was to examine the effect of fatigue from maximal tennis hitting on skilled tennis performance. Eighteen senior county tennis players (9 males, 9 females) volunteered to participate in the study. Their mean (+/- s(mean)) age and body mass were as follows: males 20.7 +/- 0.9 years and 60.6 +/- 2.7 kg respectively, females 21.7 +/- 0.6 years and 71.5 +/- 1.8 kg respectively. The players undertook two performance tests, both against a tennis ball serving machine, on an indoor tennis surface: (1) a pre- and post-skill test of groundstrokes and service; (2) the Loughborough Intermittent Tennis Test (4 min work plus 40 s recovery) to volitional fatigue. Body mass decreased by 1.5% (P < 0.0001). Mean heart rates differed between rest, post-warm-up and all intermittent test values (P < 0.01), between the pre- and post-skill tests (P < 0.0001) and between bouts and recoveries (P < 0.01). Peak blood glucose and lactate concentrations were 5.9 mmol l(-1) (50% into the intermittent tennis test) and 9.6 +/- 0.9 mmol x l(-1) (25% into the test) respectively. Mean time to volitional fatigue was 35.4 +/- 4.6 min. Groundstroke hitting accuracy decreased by 69% from start to volitional fatigue in the intermittent test (P < 0.01). Service accuracy to the right court declined by 30% after the intermittent tennis test. The results of this study suggest that fatigue was accompanied by a decline in some but not all tennis skills.