科学概念教学是科学教育的重要内容。2022年4月我国颁布了《义务教育科学课程标准》（2022年版），明确指出科学课程的目标是要培养学生的“科学观念、科学思维、探究实践、态度责任”等核心素养；其中科学观念强调在理解科学概念的基础上形成对客观事物的总体认识，是其它素养的基础，可见概念教学的重要性。“物质的变化”单元作为教育科学出版社小学六年级下册的重要内容，相关概念也是学生后续学习的基础。在开始本单元内容学习前，学生已经在生活、学习中形成了多种多样的迷思概念，阻碍了学生对科学概念的理解和掌握。因此，本研究根据“物质的变化”单元教学特点，在对学生“物质的变化”单元迷思概念探查的基础上，选择PDEODE策略（Predict -Discussion -Explain -Observe -Discussion - Explain，即预测—讨论—解释—观察—讨论—解释）应用于单元教学中，探究其是否能有效促进学生“物质的变化”单元迷思概念的概念转变。

本研究：首先，利用一般二阶测试题探查了学生“物质的变化”相关迷思概念，基于2022年版课程标准和教材内容分析，结合对五位一线科学教师、六名小学六年级学生的访谈结果，编制了用于探查学生“物质的变化”单元迷思概念的一般二阶测试题；其次，开展了概念转变教学策略有效性的准实验研究，选择广州市黄埔区某小学，实验班36人，对照班36人，实验班采取PDEODE策略教学，对照班采取近似常规教学的POE策略（Predict - Observe - Explain，即预测—观察—解释），在教学干预前后分别对两个班级进行测试，通过对前后测数据的分析，验证PDEODE策略对学生概念转变的效果；最后，在教学实施四周后对实验班、对照班实施延时后测，探索两种不同教学策略对学生概念转变的维持效果。

研究结果表明：（1）学生在“物质的变化”单元上对“物质”“物理变化”“化学变化”等核心概念存在不同程度的迷思概念。在“物质”概念上，学生主要依据感觉判断，错误地认为空气不是物质；在“物理变化”概念上，学生简单认为物质的状态、形状、大小发生变化就是物理变化，没有将产生的变化和新物质联系起来；在“化学变化”概念上，仅从物质变化的表象对化学变化进行判断，没有认清化学变化的本质是有新物质产生。（2）教学干预后实验班、对照班的测试成绩均有显著提升，实验班的平均分显著高于对照班，即PDEODE策略教学对学生概念转变效果优于POE策略。（3）实验班延时后测成绩显著高于对照班，即PDEODE策略对学生概念转变的维持性优于POE策略。本研究丰富了PDEODE策略应用的学段和内容，同时也为小学科学“物质的变化”单元的教学提供了新的思路和方法。

In April 2022, China promulgated the Science Curriculum Standards for Compulsory Education, which clearly states that the goal of the science curriculum is to develop students' core literacies such as "scientific concepts, scientific thinking, inquiry and practice, and attitude and responsibility", among which scientific concepts are emphasized on the basis of understanding scientific concepts. The concept of science emphasizes the formation of a general understanding of objective things based on the understanding of scientific concepts, which is the basis of other literacies. The unit "Changes in Matter" is an important part of the second grade of the sixth grade of the Educational Science Press, and the related concepts are also the basis for students' subsequent learning. Before starting this unit, students have already formed a variety of myths in their lives and studies, which hinder their understanding and mastery of scientific concepts. Therefore, based on the characteristics of the "Changes in Matter" unit, this study selects the PDEODE strategy (Predict -Discussion -Explain -Observe -Discussion - Explain) to be applied in the unit to investigate whether it can effectively promote the conceptual transformation of students' mythical concepts in the "Changes in Matter" unit.

This study: First, the general second-order test questions were used to explore students' myths related to "changes in matter". Based on the analysis of the curriculum standards and the content of the textbook, and the results of interviews with five front-line science teachers and six sixth-grade students, the general second-order test questions were developed to explore students' myths related to the unit "changes in matter"; Secondly, a quasi-experimental study on the effectiveness of teaching strategies for conceptual transformation was conducted, selecting an elementary school in Huangpu District, Guangzhou, with 36 students in the experimental class and 36 students in the control class; the experimental class adopted the PDEODE strategy for teaching and the control class adopted the POE strategy (Predict - Observe - Explain), which approximates conventional teaching; the two classes were tested before and after the teaching intervention, and the effect of the PDEODE strategy on students' conceptual transformation was verified through the analysis of the data from the pre and post tests; Finally, a delayed post-test was administered to the experimental and control classes four weeks after the instructional implementation to explore the effects of the two different instructional strategies on maintaining students' conceptual shifts.

The results of the study show that: (1) students have different degrees of confusion about the core concepts of "matter", "physical change" and "chemical change" in the unit of "Changes in Matter". (1) Students have different degrees of myths about the core concepts of "matter", "physical change" and "chemical change". In the concept of "matter", students mainly rely on their sensory organs to make judgments and mistakenly think that air is not matter; in the concept of "physical change", students simply think that a change in the state, shape, and size of matter is a physical change and do not connect the resulting change with the new matter. In the concept of "chemical change", students judge chemical change only from the appearance of material change, but do not recognize that the essence of chemical change is the production of new substances. (2) The test scores of both the experimental and control classes improved significantly after the instructional intervention, but the mean scores of the experimental class were significantly higher than those of the control class, i.e., the effect of teaching the PDEODE strategy on students' conceptual transformation was better than that of the POE strategy. (3) The experimental class had significantly higher post-test scores than the control class, i.e., the PDEODE strategy was better than the POE strategy in maintaining students' conceptual change. This study has enriched the school period and content of PDEODE strategy, and also provided new ideas and methods for teaching the elementary science unit of "Changes in Matter".