The kinematic differences between accurate and inaccurate squash forehand drives for athletes of different skill levels     

Benjamin K. Williams  Ross H. Sanders  Joong Hyun Ryu  Philip Graham-Smith  Peter J. Sinclair 《Journal of sports sciences》2020,38(10):1115-1123

ABSTRACT

To maintain the accuracy of squash shots under varying conditions, such as the oncoming ball’s velocity and trajectory, players must adjust their technique. Although differences in technique between skilled and less-skilled players have been studied, it is not yet understood how players vary their technique in a functional manner to maintain accuracy under varying conditions. This study compared 3-dimensional joint and racket kinematics and their variability between accurate and inaccurate squash forehand drives of 9 highly skilled and 9 less-skilled male athletes. During inaccurate shots, less-skilled players hit the ball with a more open racket, demonstrating a difference in this task-relevant parameter. No joint kinematic differences were found for accuracy for either group. Coordinated joint rotations at the elbow and wrist both displayed a “zeroing-in” effect, whereby movement variability was reduced from the initiation of propulsive joint rotation to a higher consistency at ball-impact; potentially highlighting the “functionality” of the variability prior to the impact that enabled consistent task-relevant parameters (racket orientation and velocity) under varying conditions. Further, highly skilled players demonstrated greater consistency of task-relevant parameters at impact than less-skilled players. These findings highlight the superior ability of highly skilled players to adjust their technique to achieve consistent task-relevant parameters and a successful shot.  相似文献   

Reducing the prior-knowledge achievement gap by using technology-assisted guided learning in an undergraduate chemistry course     

Anna J. Lou  Susanne M. Jaeggi 《科学教学研究杂志》2020,57(3):368-392

There have been many practical obstacles for teachers to implement evidence-based educational technology, especially in STEM classrooms. By implementing learning principles related to Cognitive Load Theory, we developed an innovative Technology-Assisted Guided Learning (TAGL) approach and its web-based instructional tool, combining expertise from educational research and best teaching practices to enhance guided student-centered learning in chemistry. A total of 185 community college students were randomly assigned to learn stoichiometry through either TAGL or one of two active control interventions, traditional direct instruction and Khan Academy, a widely used web learning platform. We found that the TAGL group significantly outperformed both active control groups immediately after instruction, and furthermore, despite the fact that all groups received additional instruction in stoichiometry, the beneficial effects of TAGL compared to the control groups were maintained a month later. Notably, TAGL was able to eliminate the achievement gap between students with low prior knowledge and students with high prior knowledge. Furthermore, prior-knowledge activation was found to be especially beneficial for students with low prior knowledge. Our work contributes to existing research in learning theories and provides new insight toward the development of more effective and adaptive instructional designs. By translating research into practice, this study demonstrates the great potential of using innovative computer-based technology to improve student learning for all.  相似文献