POE教學策略對於九年級學生學習「凸透鏡成像」概念改變之研究

Abstract

本研究探討「預測-觀察-解釋（Prediction-Observation-Explanation, POE）」教學策略對於學生學習凸透鏡成像概念之效果，以及在POE教學過程中，學生概念改變的情形。研究對象為國中九年級學生，共34人。研究工具為測驗卷及學習教材，其中測驗卷為自編的「凸透鏡成像概念測驗卷」（α＝.74），經由一位科教專家與兩位理化教師檢視修正再經試測後完成，測驗卷共有11題，題目分為兩大類，第一類為基本概念題共六題，第二類為迷思概念類型題共五題。學習教材以學習單的方式呈現，依據學生凸透鏡成像迷思概念及POE教學策略設計而成。進行前測、教學及後測，以描述性統計、相依樣本t考驗、卡方考驗分析學生在前、後測及學習單的作答結果。研究結果發現：1）POE教學對於學生學習凸透鏡成像的基本概念（透鏡性質、凸透鏡成像原理、光向四面八方傳播），以及解決凸透鏡成像迷思概念均有顯著成效（P＜.05）；2）學生在面對凸透鏡被不透明物遮蔽的成像問題時，不同情境下（遮凸透鏡上半部、下半部、鏡心及周圍）往往表現出不同的迷思概念，在一系列的實驗過程中，雖已經過凸透鏡上半部、下半部被遮住的情境，但預測時仍難以將所學概念應用於凸透鏡鏡心被遮蔽的情境，經觀察產生認知衝突後，就能做出正確的解釋並將正確概念應用在遮住凸透鏡周圍的情境。本研究建議：1）教師在教授凸透鏡被不透明物遮蔽的成像時，能提供多個情境；2）教授光向四面八方傳播概念時，可將有成像時的光源、凸透鏡、屏幕的位置固定在軸線上，然後以光源為圓心，軸線為半徑，做球形繞動。形成成像的球體，讓學生觀察；3）每教授完一個概念，教師應留有讓學生思考的時間。Investigated was the effectiveness of POE（Prediction-Observation-Explanation） teaching strategies on students’conception and the students’ conceptual change about images formed by convex lens. Thirty four ninth graders were involved. The instruments were paper test which related to images formed by convex lens（α＝.74）and worksheets. The test consisted of 11 questions classified into two parts:the first part was six questions related to real images formed by convex lens, lens properties and light dispersion；the second part was five misconception questions. The test had been revised and examined by one science educator and two science teachers . Worksheets was designed based on POE teaching strategy and misconceptions of images formed by convex lens. One-group pretest-posttest design was adapted. The results were analysed through descriptive statistics, dependent t-tests and chi-square tests. The results showed : 1) POE teaching strategy could significantly ( P＜.05）help students understand the basic conceptions including images formed by convex lens, lens properties and light dispersion and misconceptions；2) student showed different misconceptions of images when different parts of convex lens (the upper part, the lower part, the center, the circumference) were covered respectively by opaque objects；3) students had difficulty to apply what they had learned about the results when the upper and lower parts of convex lens were covered to the center of the convex lens was covered. When students’ predictions were wrong, they would have conflicts cognitively, then they could make corrections. Recommendations were 1)teachers should provide different situations when teaching image formations, especially for different part of the convex lens was covered by opaque objects；2)when there was clean images, teacher should fix the positions of the light source, convex lens and screen, and hold the light source as the center of a circle, the axis as the radius, moving spherically to form the spheroid of images to let students observe dispersion of light；3)after finishing one concept teaching, teacher should slow down the pace to leave time for students thinking.