Study the Students' Conceptions and Reasonings About the Transformations of Matter through their Abilities of the Conservation of Weight

Author: Bao-tyan Hwang, Shih-shiung Chen(Department of Chemistry, National Taiwan Normal University)

Abstract：

This paper was to study students' conceptions and reasonings about the transformations of matter and conservation of weight. The main purposes for conducting the study were :
l.to analyze how students perceive the transformations of matter and weight conservation when matter transformed.
2.to investigate the relationship between students' conceptions about the tansformations of mat-ter and weight conservation when substance transformed.
3.to study the relationship between students' cognitive development and weight conservation abilities when matter transformed.
The test instrument for measuring the students' conceptions is a form of group demonstration test, which was developed from the first author by referring to some of the other research results. The test consists several concepts : dissolution、evaporation、sublimation、oxidation and chemical reaction. There were 775 students selected from six junior high schools as the subjects for the study.
The results of this study were :
l.Three types of students' misunderstandings about the transfromations of matter were found as follows:(l)Incorrect conceptions about matter, (2)Incorrect or improper conceptions about the matter transformations, (3)Confusion between chemical change and physical change.
2.Four types of students' correct reasoning on weight conservation were found:
(l)To posses conceptions about the transformations of matter, (2)Reversibility、identity and compensation reasoning, (3)The weight is unchanged in closed system, (4)To use laws or rules, such as the low of mass conservation.
3.Four types of students' incorrect reasoning of conservation of weight were also found:
(l)To lack conceptions about the transformations of matter, (2)Only consider part of the mat-ter transformed and missing the whole situation, (3)Incorrect conceptions about matter. (4) To mislead by daily life experience.
4.The more information students acquired about the transformations of matter, experically in more complicated transformations, the easier it is for them to judge and reason correectly about the weight of matter when matter transformed.
5.The students who were able to operate formaley can easily judge and correctly reason about the weight of matter when matter transormed.

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