Students' Mental Models In Physics Experiments

Under the guidance of the mental model theory, this study conducted a semi-structured interview with forty Junior One students in a microwave popcorn experiment. It aims to explore the following issues:how do the students predict the experimental results in the context; how do they realize the characteristic and method on constructing the mental model in dealing with the relationship between such prediction and the mental mode upon the observed experimental phenomena; how do they construct the mental model according to the experimental phenomena; how do they use the mental models to solve similar problems and how to reflect and renew mental models.The evaluating indicators of this study are worked out according to the scoring standards for open tests of science made in the test and evaluation project by Ministry of Education. The students are divided into the three levels of mental models:empirical observations (10), rule explanation (20) and three levers on systematic theory (30), each of which can be subdivided. The students'mental model levels are judged corresponding to the above standards.The study finds that predicting-experimenting facilitates are beneficial for students'construction of the mental models. Low-level students present mental models by combining their knowledge and experience on the basis of experience. The mental models in the prediction phase show high level:Level I: 35%, level II:52.5%, level III:12.5%. The students' empirical models are abundant. Empiricism exerts great influence on the building of mental models, for their predictions are mostly based on experience. The mental models are rich too. The richer phenomena those students confront, the higher level of mental model they represent. In the forecast phase, male and female students perform slight difference in that the latter are superior to the former. In the case of complementary models, the students'mental representation has greatly improved as a whole, without overt distinction between the two genders. When it comes to the different models, the students'cognition conflicts strongly. But there is no qualitative change or big differences between the two genders. Low-level students enjoy a high level mental model. However, they also counter great difficulty in the conversion process. The students display diversity in the way of changing their mental models, including giving up the original mental models, adding constraints; turning to peripheral theories to explain different phenomena, and combining different theories to simplify the model. In the model validation stage, mainly the following five circumstances occur:ignoring the incompatibility model; rejecting incompatible models; re-explaining incompatible models; changing peripheral theories; changing the original model. The students' mental models are, to a large extent, affected by the experimental results. Comparing the pre-and post-validation of the complementary models, we find an exponential increase in the number of students who begin to build a correct mental model. Compared with facing complementary models,64.9% of the students ignored using different models, refused to use different models, hold different model and can not make a good use of different models while facing the incompatible models. But different model played a very good role in realizing conflicts.35.1% of the students have reached the lever on changing the theoretical theory or changing the external theory in order to build a new model, a better use of different experimental results.