Swimming

Abstract

The effect on drag of a Speedo Fast‐skin suit compared to a conventional suit was studied in 13 subjects (6 males, 7 females) swimming at different velocities between 1.0 and 2.0 m?s^‐1. The active drag force was directly measured during front crawl swimming using a system of underwater push‐off pads instrumented with a force transducer (MAD system). For a range of swimming speeds (1.1, 1.3, 1.5 and 1.7 m?s^‐1), drag values were estimated. On a group level, a statistically non‐significant drag reduction effect of 2% was observed for the Fast‐skin suit (p = 0.31). Therefore, the 7.5% reduction in drag claimed by the swimwear manufacturer was not corroborated.     

Effect of a Fast-skin 'body' suit on drag during front crawl swimming

The effect on drag of a Speedo Fast-skin suit compared to a conventional suit was studied in 13 subjects (6 males, 7 females) swimming at different velocities between 1.0 and 2.0 m.s-1. The active drag force was directly measured during front crawl swimming using a system of underwater push-off pads instrumented with a force transducer (MAD system). For a range of swimming speeds (1.1, 1.3, 1.5 and 1.7 m.s-1), drag values were estimated. On a group level, a statistically non-significant drag reduction effect of 2% was observed for the Fast-skin suit (p = 0.31). Therefore, the 7.5% reduction in drag claimed by the swimwear manufacturer was not corroborated.     

Using computer animation and illustration activities to improve high school students' achievement in molecular genetics

Our main goal in this study was to determine whether the use of computer animation and illustration activities in high school can contribute to student achievement in molecular genetics. Three comparable groups of eleventh‐ and twelfth‐grade students participated: the control group (116 students) was taught in the traditional lecture format, whereas the experimental groups received instructions that integrated a computer animation (61 students) or illustration (71 students) activities. We used three research instruments: a multiple‐choice questionnaire; an open‐ended, written questionnaire; and personal interviews. Five of the multiple‐choice questions were also given to students before they received their genetics instruction (pretest). We found that students who participate in the experimental groups improved their knowledge in molecular genetics compared with the control group. However, the open‐ended questions revealed that the computer animation activity was significantly more effective than the illustration activity. On the basis of these findings, we conclude that it is advisable to use computer animations in molecular genetics, especially when teaching about dynamic processes; however, engaging students in illustration activities can still improve their achievement in comparison to traditional instruction. © 2007 Wiley Periodicals, Inc. J Res Sci Teach 45: 273–292, 2008     

Meta-Theoretical Contributions to the Constitution of a Model-Based Didactics of Science

There is nowadays consensus in the community of didactics of science (i.e. science education understood as an academic discipline) regarding the need to include the philosophy of science in didactical research, science teacher education, curriculum design, and the practice of science education in all educational levels. Some authors have identified an ever-increasing use of the concept of ‘theoretical model’, stemming from the so-called semantic view of scientific theories. However, it can be recognised that, in didactics of science, there are over-simplified transpositions of the idea of model (and of other meta-theoretical ideas). In this sense, contemporary philosophy of science is often blurred or distorted in the science education literature. In this paper, we address the discussion around some meta-theoretical concepts that are introduced into didactics of science due to their perceived educational value. We argue for the existence of a ‘semantic family’, and we characterise four different versions of semantic views existing within the family. In particular, we seek to contribute to establishing a model-based didactics of science mainly supported in this semantic family.     

In Sickness and in Health

Science & Education - In the context of the current COVID-19 pandemic, we deem of importance the identification of what content is privileged in secondary schools around health and disease....     

Automated LED tracking to measure instantaneous velocities in swimming

In this paper a video-based method to automatically track instantaneous velocities of a swimmer is presented. Single cameras were used to follow a marker (LED) attached to the body. The method is inspired by particle tracking techniques, traditionally used in the field of fluid dynamics, to measure local velocities of a fluid flow. During the validation experiment, a white LED was attached to the hip of a swimmer together with a speedometer. A swimmer performed four different stroke types. The velocity profiles using LED tracking were captured and showed less noise than the speedometer measurements. Only at times when the marker disappeared above the water surface due to body role in front crawl and backstroke swimming did the LED tracking fail to capture the athlete’s motion. The algorithm was tested in a 2D case with a single LED to illustrate the proof of principle, but should be suitable for implementation in a 3D analysis or multiple LED analysis.