Investigating the Effectiveness of a Constructivist-based Teaching Model on Student Understanding of the Dissolution of Gases in Liquids Muammer C¸ alık, 1,4 Alipas ¸ a Ayas, 2 Richard K. Coll, 3 Suat U ¨ nal, 2 and Bayram Cos ¸ tu 2 The research presented in this paper consisted of an investigation of the effectiveness of a four- step constructivist-based teaching activity on student understanding of how pressure and temperature influence the dissolution of a gas in a liquid. Some 44 Grade 9 students (18 boys and 26 girls) selected purposively from two school classes in the city of Trabzon, Turkey participated in the study. Students’ understanding were evaluated from examination of two items from a purpose-designed solution concept test, face-to-face semi-structured interviews and examination of students’ self-assessment exercises. Statistical analysis using two-way ANOVA of student test scores point to statistically-significant differences in test and total scores (p < 0.05) suggesting that the teaching activities employed help students achieve better conceptual understanding. Further, no statistically significant differences were seen between post-test and delayed test scores, suggesting that teaching the activities enable students to retain their new conceptions in their long-term memory. However, in a few instances the activities resulted in the development of new alternative conceptions, suggesting teachers need to be conscious of the positive and negative effects of any teaching intervention. KEY WORDS: four-step constructivist teaching activity; solution chemistry; effects of temperature and pressure to dissolution of gas in a liquid; conceptual change. In the early 1990s, Fensham asserted that ÔThe most conspicuous psychological influence on curriculum thinking in science since 1980 has been the con- structivist view of learning’ (Fensham, 1992, p. 801). Constructivism as Fensham sees it, requires teachers to deconstruct traditional objectivist conceptions of the nature of science and knowledge acquisition, and to evaluate their personal epistemologies, teaching practices that result from these epistemologies, and seek to develop appropriate educative relationships with their students. Despite some reservations of constructivism, and its many variants (see, e.g., (Matthews, 2002), this learning theory has exerted considerable influence on thinking on educational research and thinking about teaching and learning. The basic premise of constructivism is that each individual mentally constructs understanding, rather than acts as a passive receiver of knowledge. This construction is mediated by the individual’s prior knowledge of actual and related concepts, and is influenced by a variety of socio-cultural factors (leading to variants’ of constructivism such as social and contextual constructivism, Good et al., 1993). However, as Matthews (2002) and others point out, there is not necessarily any simple, coherent link 1 Department of Science Education, Giresun University, 28200, Giresun, Turkey 2 Department of Secondary Science and Mathematics Education, KaradenizTechnical University,61335, So¨ g˘u¨ tlu¨ –Trabzon, Turkey 3 Centre for Science & Technology Education Research, University of Waikato, Hamilton, New Zealand 4 To whom correspondence should be addressed; E-mail: muammer38@hotmail.com Journal of Science Education and Technology, Vol. 16, No. 3, June 2007 (Ó 2006) DOI: 10.1007/s10956-006-9040-4 257 1059-0145/07/0600-0257/0 Ó 2006 Springer ScienceþBusiness Media, LLC.