A Comparison of Instruction Effectiveness between the Experiment of Precipitation and the Experiment with Ball and Stick Model Related to 'Law of Definite Proportions'

This study compared the instruction effectiveness between experiments of precipitation and a ball & stick model related to the 'Law of Definite Proportions'of 9th grade science in this study. The subjects were 250 students in the 9th grade. They were divided into two groups, an experimental group and a model group. The results showed that the ratio of thought in which the elements were divided in the solutions and the ratio of thought in which a new compound was created when the two solutions were mixed were higher in the precipitation experiment group than in the model group. The two groups were not different in terms of the ratio of thought related to the reason for the creation of the precipitate. The ratio of thought pertaining to incorrect answers was high, implying that the two strategies were not effective in correcting students'thoughts. However, the ratio of finding patterns from the measuring data in the model group was higher than in the experimental group. However, the ratios of 'definite proportions'inference in the bonding of the reactants were similar in the two groups. From these data, we concluded that the inference of the 'Law of definite proportion'from experiments or models was not suitable for middle school students.