[[alternative]]Developing a two-tiers test to diagnose different types of misconceptions of gas among secondary school students

[[abstract]]This research is based on “Microscopic Gas Model” to develop a two-tier test that intend to diagnose different types of misconceptions of gas among secondary school students at different grades and figure out students’ mental model behind each type of misconception. The respondents of this research are 302 tenth and eleventh grade school students and 368 seventh, eighth, and ninth grade students who study in the same junior high school in Taipei. The major findings of this study are summarized as follows：1. The students’ understanding about gas properties is positively correlated with students’ grades. 2. The students’ perceptions of gas pressure are misled. Most students thought that gases exert pressure through different gas volatilities, molecular weight, and the degree of push. However, gases exert pressure because their particles constantly move around and collide with the walls of the container holding the gas. 3. In terms of motions of two types of gases, the students perceive that the gases’ velocities are equal under the same pressure, but they have not got the idea that velocities are also affected by molecular weight. 4. The students thought that gas volatility represents its speed of motion, but in fact, gas volatility represents its tendency of oxidation. This misconception becomes less serious as the students with higher grades. 5. As the grade gets higher, it is not necessary to develop better conceptions with the dynamic nature. This research provides an empirical foundation for next step large-scale study, which could result in better understandings of the types of misconceptions and the spread of each type held by different levels of ages. Teachers might furthermore take research results as reference to clarify students’ misconceptions revealed by the study.