Understanding Mental Models of Dilution in Thai Students (original) (raw)

This study investigated Indonesian and Japanese students’ understandings of macroscopic and submicroscopic levels of representing matter and its changes and the difficulties they have with these concepts. A multiple-choice questionnaire was constructed and delivered to 447 Indonesian and 446 Japanese public senior high school students. The data were analyzed using quantitative and qualitative methods. The findings of the study show students’ understandings of macro- and submicroscopic levels are stronger for higher-grade levels, except that the Indonesian students’ pattern is slightly different. The average percentage of students responding correctly on the macroscopic level ranges between 62% and 69% (Indonesia) and between 58% and 73% (Japanese), whereas on the submicroscopic level ranges between 56% and 62% (Indonesian) and 44% and 66% (Japanese). Their understandings of the macroscopic level, however, are higher than for the submicroscopic level. The soundness of students’ understandings of the concepts increases with grade level, except for Indonesian pattern slightly different. The average percentage of students responding correctly ranges between 37% and 48% (Indonesian) and between 28% and 52% (Japanese). Furthermore, students’ level of sound understandings of the concepts is lower than their understandings on either the macroscopic level or the submicroscopic level. It is found that students have great difficulties with and hold some alternative conceptions of the concepts of homogeneous mixtures, phase changes from solid to liquid, and phase changes from solid to gas. The study has implications, for example, the use of several routes to meaningful learning and the careful use of technical words.

Knowledge of chemistry involves abstract concepts and it should be explained in three representative levels, namely, macroscopic representative level, sub-microscopic representative level and symbolic representative level [7]. The first concrete and actual level is the macroscopic level which contains visible and tangible concepts or processes; the second level is about the actual phenomenon which explains the sub-microscopic level depicting entities which are too small to be seen under an optical microscope and, the bonding within and between them and the third level is symbolic, which involves figures, signs, symbols, letters, equations, mathematical representations and formulae. The success of students in mastering the concepts of Chemistry is closely related to their ability to create relationships among the three levels of representation. The different levels of representation are integral to understanding chemical phenomena, a fact that makes learning in chemistry challenging....

This mixed method study mainly explored how the extent of pre-service chemistry teachers' understanding of the particle nature of matter (PNM) affects their understanding of solution chemistry in the context of multirepresentational (MR) instruction. The ultimate goal was to describe the levels of understanding of specific solution chemistry concepts of a group of participants with a high understanding of the PNM and a group with a low understanding of the PNM before and immediately after MR instruction. Data sources included questionnaires about the PNM and interviews on solution chemistry. Data from these sources were coded and analyzed using quantitative and qualitative methods. There was a statistically significant difference between the results obtained for the understanding of solution chemistry before MR instruction for participants with a high understanding of the PNM and those with a low understanding of the PNM. Both groups of participants exhibited substantial progress towards the scientific understanding of solution chemistry from pre-to post-instruction; however, the participants with a high understanding of the PNM still outperformed those with a low understanding of the PNM in terms of developing a more scientific conceptual understanding of the topic after the MR instruction. Moreover, when the participants were provided with an opportunity to view dynamic visual particulate representations of phenomena to support verbal representations, about two-thirds of the participants from both groups were able to develop a scientific understanding of dissolution regardless of the extent of their understanding of the PNM. Yet, the findings suggested that the participants with a high understanding of the PNM were more likely to develop a scientific understanding of a particular concept (e.g., supersaturated solutions) in solution chemistry even without viewing the available visual particulate representations of the phenomenon.

This study involved the development of a two‐tier diagnostic instrument to assess Thai high school students’ understanding of acid–base chemistry. The acid–base diagnostic test (ABDT) comprising 18 items was administered to 55 Grade 11 students in a science and mathematics programme during the second semester of the 2008 academic year. Analysis of students’ responses from this study followed the methodology outlined by Çalik and Ayas. The research findings suggest that the ABDT, the multiple choice diagnostic instrument, enables researchers and teachers to classify students’ understanding at different levels. Most students exhibited alternative conceptions for several concepts: acid–base theory, dissociation of strong acids or bases, and dissociation of weak acids/bases. Interestingly, one of the concepts that students appeared to find most difficult, and for which they exhibited the most alternative conceptions, was acid–base theory. Some alternative conceptions revealed in this study differ from earlier reports, such as the concept of electrolyte and non‐electrolyte solutions as well as the concentration changes of H3O+and OH− in water. These research findings present valuable information for facilitating better understanding of acid–base chemistry by providing insight into the preventable and correctable alternative conceptions exhibited by students.

Due to their abstract nature, the mole concept and solution concentration are difficult for students to understand and apply to stoichiometric calculations. This study was designed to investigate students' perceptions and difficulties in solving problems related to the mole concept and solution concentration. Thirty-eight students (18-19 years old) who were pursuing science related programmes from a private university college in Malaysia participated in the study. Students were asked to answer twenty-five open-ended questions on the mole concept and solution concentration. Analysis of students' responses revealed that they were not able to connect the mole concept with mass and number of particles. Students were also grappling to answer problems regarding concentration and dilution. This study suggests that it is important to determine whether students' difficulties to master the concepts are due to lack of knowledge or the presence of alternative frameworks so that so that pedagogical instruction can be modified. This study was part of a larger research project where students' responses on this open-ended test will be used to get a greater generalizability in order to construct the alternatives to the four-tier multiple choice (4TMC) instrument to identify students' alternative frameworks on these concepts.

This study examines an example of the alternative conceptions and conceptual errors of students at the higher education level in a scientific context. It begins by introducing the significance and characteristics of preconceptions and alternative ideas or alternative conceptions, highlighting their impact on students’ misconceptions. Using the dissolution of a gas (oxygen) in a liquid (water) as the case study, and based on the answers to a questionnaire, this work analyzes the responses by university students which, in most cases, lack scientific rigor. The questionnaire used in this study has been designed in such a way that students provide three types of answers: the first is a yes/no/do not know question; the second is a short answer question to briefly explain the previous answer; and the third is a drawing answer question in which students are required to interpret the phenomenon at the molecular level by drawing a picture. Surprisingly, minimal differences were observed betw...