Learning conservation of matter in phase changes

Abstract

Learners regard Chemistry as one of their most difficult courses at secondary and undergraduate levels, because they have to link several modes of representing matter and their interactions. Phase changes are one of the topics that learners of Chemistry experience problems with. On microscopic level phase changes can be explained in terms of the particulate nature of matter. During a phase change the outward appearance of a substance change, while the substance itself remains the same. In order to learn this concept, learners performed experiments on conservation of mass in an empirical study. The empirical study was conducted amongst 46 Grade 10 learners of Kgabutle High School in the Bojanala region, in the North-West Province, South Africa, following the Curriculum Statement for Physical Sciences. The investigation was done with the aid of a questionnaire. This was followed by an intervention that consisted of guided inquiry lessons aimed at enhancing the learners' understanding of conservation of matter in phase changes. Constructivist learning principles were implemented in the lessons. The effectiveness of the intervention was determined by administering the same questionnaire as pre- and post test and calculation of normalized learning gains. The results of the empirical study were used to identify alternative conceptions and other problems that hampered learners' understanding, such as language and in-depth knowledge about the kinetic molecular theory. Constructivist principles of learning are recommended to be used to enhance learners' understanding of conversation of matter in phase changes.