| Summary: | 碩士 === 慈濟大學 === 教育研究所 === 94 === The purpose of the reasearch, which takes the evaluation of conceptions of the optics in junior high school for example, is to investgate the development of a two-tier diagnostic instrument for the scientific conceptions. The first tier of each item has a content response . The second tier consists of reasons bases on students’ responses to interviews, open-ended questions, and previous research.
The research is mainly based on the theory of Treagust (1988), and I recorrect the theory to get it. The second tier of each item of the two-tier instrument is designed to become multiple choices for avoiding guessing and maybe there’s not only one misconception of the same guestion.
In reliability, I use “cronbanch α” of “coefficient of internal consistency”. Each question has two different tier of choices. If the tester gets the whole right answers, they will get one point. The cronbanch α of the two-tier diagnostic instrument in this research development, which is checked by SPSS, is .8166.
In the view of validity, I utilize “content validity” and “construct validity”. In order to make the content more valid, I ask the experts to check up the correctness and representive of the instruments, which includes propositional knowledge statements, opened-ended questions and the two-tier diagnostic instruments, and then I use secificiation grid to check that the diagnostic test fairly covers the propositional knowledge statements. The construct validity to evaluate the two-tier diagnostic instrument is to analyze the multiple choices and the scores differences of each question in two groups of students, that includes one group has learned and the other hasn’t.
The two-tier diagnostic instrument, which is developed by this research, can not only know what the students’ misconceptions are， but also deeply understand the percentage of the students who have the misconceptions, even know what the students’ unchangeable misconceptions in the unit are.
In addition to other ways of diagnostic instrument, the two-tier diagnostic instrument has the characteristics, quickness and directness, diagnosing the misconceptions of students.
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