- 期刊
高中學生的「失重」概念之研究
A Study on the Weightlessness Concepts of Senior High School Students
摘要
在懸吊鋼繩斷裂而自由落下的電梯中，站在磅秤上的人測得的重量為零，所以說人處於「失重」狀態。如果根據一般教科書採用的「重量即物體所受重力」或「物體所受重力的大小」來推論，如此一來，物體失重時其所受重力也是零。可是，失重時真的沒有重力作用嗎？本研究旨在探討高中學生在失重教學後所建構的「失重」概念。研究對象為學過力學的高二學生96人。研究方法以量化的調查研究為主，質性的個案訪談為輔。研究工具為自編的「失重概念問卷」，以霍金體驗失重飛行的新聞為背景，題目形式採用「事實－理由」兩階段設計，並在每階段另增加一層學生對自己作答的「信心加權」評分，而形成兩階段四階層測驗。在「理由」階段，前測問卷為開放式，後測則為是非題，並將信心加權改為逐題對其說服力評分（1最低，5最高，0為「非」）。研究發現：約四成學生知道失重並不是失去重力而是感受不到重量，而同時能正確說出失重飛行時，何時會產生失重狀態者，僅剩8.5%。學生的失重概念心智模式可歸納成七種：測量說、離心力說、漂浮說、高度說、大氣說、零重力說、及直覺說。重量的重力定義可能導致失重即失去重力的錯誤推論，建議教師教學時應釐清重量與重力的概念。
並列摘要
A person standing on a scale in a free-falling elevator is weightless because the scale reading is zero. According to the gravitational definition of weight adopted by common textbooks, the weight is considered a gravity force and zero weights imply no gravity force exerted on the person. But is there really no gravity force? The purpose of this study was to explore the concepts of weightlessness that senior high school students possessed after the instruction using gravitational definition of weight. The participants were 96 eleven-graders enrolled in physics classes and completed mechanics course including the concept of weightlessness in a public high school. A survey was involved primarily and interviews were conducted with students as well. The instruments used in this study including pretest and posttest four-tier (fact-confidence-reason-confidence/persuasiveness) questionnaires concerning weightlessness concepts were developed, based on the news report about Dr. Stephen Hawking's weightless flight. Either in the pretest or posttest questionnaire, the fact-tier question is multiple-choice used to measure content knowledge, and the confidence-weighting tier is used to measure the strength of respondent’s conceptual understanding. However, the reason-tier questions in the pretest questionnaire are open-ended while they consist of some reason items with 6-point likert Scale (0=incorrect, 1=lowest persuasive, 5=highest persuasive) that designed to rate the persuasiveness of the item instead of confidence-weighting in the posttest questionnaire. The results showed that about 40% of students could perceive that the weight is zero and the gravity force does not change in the weightless situation. Only 8.5% also succeeded in answering when the passenger experiences weightlessness during a weightless flight. Students’ cognitive models of weightlessness were classified into seven categories: there were Measure Model, Centrifuge Force Model, Float Model, Altitude Model, Atmosphere Model, No-gravity Model, and Intuition Model. The gravitational definition of weight may result the inaccurate inference of ”no weight, no gravity”. Teachers should distinguish ”weight” of an object as a contact force exerted on its support and ”gravity” as a non-contact force exerted on the object by the Earth.