[[alternative]]To investigate ninth graders' learning and conceptual change of acidity and alkalinity via the use of multimedia instruction

[[abstract]]The conception about acids and bases is important in the science curriculum. It not only closely relates to daily life and natural phenomenon, but also play a pivotal role in the development of chemistry history. The main purpose of this study was to explore the comprehensive level of our junior high school students after the instruction of the unit about acids, bases and salts by multimedia and animation. The change of misconceptions and metal models about acids, bases and salts were investigated as well. In this study, the abstract conception of the acidity and alkalinity was presented with the software, FLASH, such as the ionization of the acid solution and the base one, the neutralization, as well as the hydrolysis of the salts and water, after the neutralization. 74 junior high school students of 9th grade in two classes were sampled randomly from a local school in Taipei County. The study focus on integrating the conceptions in the units about acids, bases and salts from the textbooks for junior high school, and conforming the goals of the instruction. According to the above, the researcher designed the animations and the slides for instruction, and then the teaching aids were used in both group A and group B. Both of the groups took the pretest, posttest and extensive test which were constructed by the two-tiers questionnaire in sequence. 6 students from each group were interviewed individually right after the posttest and extensive test, and the results of the interviews represented the changes of the students’ misconceptions and mental models. The results of the study were as follows. In the comparison of the veracity after the posttest and the pretest, the veracity of the group A was at the significance level (p=0.012), and so was that of the group B (p=0.000). This showed us that the instruction could influence the conceptual leaning about the unit in both of the groups. But after using the different instruction sets, the comparison between the two groups was not at the significance level. In other words, the difference of the both instruction sets couldn’t affect the students’ learning. After the extensive test and the posttest, both of the groups’ veracity was not at the significance level. That is, the conceptual change was not obvious after the extensive test. The extensive test which was taken by both of the groups in the six weeks after the end of the posttest received that, the comparison between the two groups was not at the significance level. It indirectly showed that the difference of the both instruction sets couldn’t affect the extensive test. In the comparison and analysis of the records of two interviews, sampled students were not consistent in the different concepts. The maintenance of misconceptions and the change of the misconception type were obvious in the students of middle and low achievement level; but the students in the high achievement level had similar situation in some conceptions such as the ionization of the weak acids and weak bases to dilute, the neutralization of acids and bases, the conception of a solution dissolve gas either acidic or basic. But no matter what level the students’ achievement belonged to, the misconceptions always existed. In all of the misconception about the units, the main mental models were shown as follows. A phenomenon model and a name-symbol model in the acidity or alkalinity of a solution; a strength model, a quantity model, a name model and an electricity neutral model in the neutralization of acids and bases; a converse-ionization model, a concentration model and a galvanization model in the conception of a solution dissolve gas either acidic or basic; a strength model, a quantity model, a converse- temperature model in the conception of the strength of acids and bases and the concentration of H＋;and an immutable model, a volume model, a concentration model and a converse- equilibrium model in the conception of the weak acids and bases to dilute.