This study intended a research on the types of naive mental models junior high school students used in order to understand electric heating, and also to research the possibility that their models might change from unscientific models to scientific models after scientific experiments performed by students. We found 11 types of naive models, which could be divided into two categories : "scientific models", and "unscientific models". The majority of the subjects showed "scientific models" at the time of the study. After the experiment, many subjects having unscientific models as their naive models, changed to scientific models while those who had scientific models in the beginning supported models with increasingly scientific sophistication. On the other hand, it was proved that one of the naive models could not be easily changed by the experiment. The above research showed that the experiment proved generally effective in changing student's naive mental models to more scientific ones.
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