This research discusses the effect of Prediction-Observation-Explanation (POE) teaching strategy on the "density" concept study among students, and their concept changes during the POE teaching. Research targets are 82 students from three eighth grade classes in a junior high school. The major researching tools are pre/post examination papers and associate study materials. The examination papers are designed and compiled by the researcher. These examination papers are inspected, revised and tested by three physics and chemistry teachers. Based on students' misconception in "density" and the POE teaching strategy, study materials are designed as worksheets. Researcher found that students have the following misconceptions: (1) incorrectly make use of "light" and "heavy" as the determination of floating and sinking; (2) wrong analogy: students concluded the floating and sinking of the objects only by the analogy with certain conditions (such as mass) between objects; (3) simple linear relationship produced misconceptions: students considered that the density would increase if mass increased given the same kind of objects. My research suggests: (1) when teaching "density", teachers should base on multiple circumstances instead of single one in order to judge whether students understand the concept, and determine their understanding of the concepts by studying their reactions under different circumstances; (2) after the completion of teaching one concept, teachers should leave more time to students to think through; (3) instead of letting students learn by reciting formulas, organizing activities for experiments can more effectively introduce students to the abstract concept from concrete operations.

本研究探討預測-觀察-解釋(Prediction-Observation-Explanation, POE)教學策略於學生學習「密度」概念之成效，以及在POE教學過程中，學生概念改變的情形。研究對象為初中二年級三個班的學生，共 82人。研究工具為前、後測驗卷及學習教材，其中前後測由研究者自行編，經由三位理化教師檢視修正再經測試後成。學習教材以學習單的方式呈現，依據學生「密度」迷思概念及POE 教學策略設計而成。研究結果發現學生仍存有如下的迷思概念：(1) 誤用「輕」、「重」做浮沉的判斷依據；(2) 錯誤的類比：學生只會抓住物體間某些條件（如質量）相同，依此類比物體彼此浮沉的情形也會相同；(3) 簡單的線性關係造成的迷思概念：學生認為同一種物體，如果質量（或體積）增加，密度也隨著增加。本研究的建議： (1) 教師在教授「密度」時，不能僅以單一情境來判斷學生對概念是否了解，應提供多個情境，藉由檢視學生在不同情境表現來判斷他們對概念的理解情度。(2)每教授完一個概念，教師應留有讓學生思考的時間。(3) 在科學概念教學過程中應用實驗活動，更能引導學生從具體的操作中學習抽象的概念，而不是讓學生利用背公式來學習。