Ninna JansoonRichard K. CollEkasith SomsookMahidol UniversityUniversity of Waikato2018-09-132018-09-132009-06-11International Journal of Environmental and Science Education. Vol.4, No.2 (2009), 147-168130630652-s2.0-66549088323https://repository.li.mahidol.ac.th/handle/20.500.14594/27556The purpose of this study was to investigate Thai students' understanding of dilution and related concepts. The literature suggests that a complete understanding of chemistry concepts such as dilution entails understanding of and the ability to integrate mental models across three levels of representation: the macroscopic, sub-microscopic and symbolic. In this work students' understanding was probed using the interview about events (IAE) approach employing open-ended questions, and also by analysis of student descriptions, and drawings. The research findings suggest that all students were able to answer open-ended questions related to dilution and related concepts. Less able students presented representations at the symbolic level and subsequently described events at the sub-microscopic and macroscopic levels. However, these latter representations typically were unrelated to the representations presented at the symbolic level. In contrast, more able students were able to present consistent representations of dilution at each level of representation. Copyright © 2009 IJESE.Mahidol UniversityEngineeringEnvironmental ScienceSocial SciencesArticleSCOPUS