本研究对广东省广州市某实验学校小学四年级两个班以溶解单元教学为例，进行准实验研究，实验班采取对话学习模式，对照班采用传统讲授式教学。验证对话学习能提高溶解单元相关概念的转变率（学生能完成溶解单元相关概念的测试题并能科学解释概念）；通过对课堂及学生学案的观察和分析，证实对话学习模式能促进学生互惠性的发展。为一线教师提供参考，帮助学生进行“溶解”单元相关概念的概念转变，并为概念转变的相关研究及对话学习模式增添实证研究。

研究结果表示，学生在学习溶解单元相关内容前，头脑中存在大量的前概念，通过分析得出影响学生前概念的因素包括：受生活经验影响、错误套用科学用语、不恰当的类比推理、直观型思考等。教学实验后，通过收集、整理、分析数据得出，实验班与对照班学生接受教学实验前后，在完成溶解单元相关概念的测试题及对相关概念的科学解释上均存在显著差异。教学实验后，实验班在完成溶解单元相关测试题及科学解释均优于对照班，实验班进步幅度也显著优于对照班。教学实验后两个月进行抽样延时后测，实验班与对照班学生在完成溶解单元相关概念的测试题中存在显著差异，实验班概念转变效果显著高于对照班。接受对话学习教学后，实验班学生的互惠性有所提高。

根据本研究得出的结果，对溶解单元教学提出四点建议：（1）重视学生前概念；（2）自我对话，引出学生前概念；（3）与他人对话，产生认知冲突；（4）与客体对话，检验假设。此外，对应用对话学习提出两点建议：（1）重视记录概念转变的过程；（2）将对话学习应用到不同年级、学科。 

Constructivism holds that different individuals have different constructions of the same phenomenon, problem and concept, so that individuals have their own unique cognitive construction ways.And the individual's construction of the concept is influenced by its life experience, learning experience and so on. Therefore, when students learn new knowledge and new concepts, they will use the existing knowledge and experience to explain them.We call it the pre-concept, that is, the concept formed by students through learning and accumulating experience in daily life without special teaching.When the pre-concept is consistent with the scientific concept, it will help students to master the concept better,otherwise the pre-concept will play a hindrance role.Thus it can be seen that the pre-concept is important for students to acquire new knowledge. Domestic and foreign scholars have realized the important influence of pre-concept, and put forward a variety of modes, strategies and methods of concept transformation, which have been applied by front-line teachers in classroom teaching.Although some results have been achieved, the cognitive reconstruction of individuals has not yet played a satisfactory effect.

In this study, two classes in the fourth grade of an experimental school in Guangzhou, Guangdong Province, took dissolved unit teaching as an example to carry out quasi-experimental research. The experimental class adopted the mode of dialogue learning and the control class adopted the traditional teaching method.To verify that dialogue learning can improve the transformation rate of the concepts related to the dissolution unit (students could complete the test questions related to the dissolution unit and explain the concepts scientifically).Through the observation and analysis of classroom and student learning plan, it is proved that dialogue learning model can promote the development of students' reciprocity. It provides reference for first-line teachers, helps students to carry on the concept transformation of dissolving unit related concepts, and adds empirical research to the related research of concept transformation and dialogue learning model.

The results show that there are a large number of pre-concept in the mind before students learn the relevant content of dissolving unit. The factors that influence the pre-concept include: influenced by life experience, misapplication of scientific terms, inappropriate analogical reasoning, intuitive thinking and so on.

 After the teaching experiment, by collating and analyzing the data, it is concluded that there are significant differences between the experimental class and the control class before and after the students accept the teaching experiment, in the completion of the test questions of the relevant concepts of the dissolution unit and the scientific explanation of the related concepts. After the teaching experiment, there were significant differences between the experimental class and the control class in completing the test questions of the relevant concepts of the dissolution unit and the scientific explanation of the related concepts, and the experimental class was superior to the control class in completing the relevant test questions and scientific explanations of the dissolution unit.

Two months after the teaching experiment, the score of the experimental class was higher than that of the control class, and the progress of the experimental class was also significantly better than that of the control class. After receiving the teaching of dialogue learning, the reciprocity of students in the experimental class was improved.

According to the results of this study, four suggestions are put forward for the teaching of dissolution units :(1)Paying attention to the student’s pre-concept ;(2) Dialogue with oneself, leading to the student’s pre-concept ;(3) Dialogue with others, resulting in cognitive conflict ;(4) Dialogue with the object, testing hypotheses.