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.     

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.     

Game-based practice versus traditional practice in computer-based writing strategy training: effects on motivation and achievement

Achieving sustained student engagement with practice in computer-based writing strategy training can be a challenge. One potential solution is to foster engagement by embedding practice in educational games; yet there is currently little research comparing the effectiveness of game-based practice versus more traditional forms of practice. In this study, the ARCS model (Keller, Perform Instr 26(8):1–7, 1987b) was used to investigate the motivational characteristics of different practice conditions. To this end, 175 students were randomly assigned to one of four experimental conditions: game-based, question-based, model-based, and writing-based practice. All students first learned strategies to write an essay introduction. Subsequently, students practiced using the strategies in the four different conditions. Game-based practice was expected to positively affect ARCS-related motivation toward practice. Results showed that students perceived game-based practice as significantly more interesting and engaging than question-based practice. However, although game-based practice was perceived more positively, only model-based and question-based practice demonstrated a beneficial impact on students’ ability to implement the writing strategies. These results underline the necessity of interconnecting motivational and instructional design when developing practice methods for computer-based writing strategy training.     

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.