Characteristics of science explanatory text of the changes in gas volume according to temperature before and after the particle nature of matter: Through the analysis of the process types of transitivity

Objectives This study is intended to provide an in-depth understanding of the difficulties of first-year middle school (7th) students beginning to deal with the particle nature of matter in explaining phenomena in terms of scientific explanationtexts. Methods For this purpose, the phenomenon of changing gas volume according to temperature was focused on science textbooks for the 6th and 7th grades. This was before and after the introduction of the particle nature of matter. The composed scientific explanatory texts were classified based on whether they contained particulate concepts. In addition, the types of processes in transitivity systems were analyzed. Results The type of process presented in the science explanatory texts of the 6th grade and 7th grade was dominated by material process. In texts that did not include the particle nature of matter, the science texts of the 6th grade and the 7th grade differed in the existential process. In the first-year middle school text, which considered the particle nature of matter, participants and circumstances showed continuity and complexity of explanation but differed mostly in attribute and relational processes. Conclusions Through the analysis of the types of processes, the difficulties of students in reading the explanatory texts before and after the introduction of the particle nature of matter were understood, and the discussion points on the method of introducing the particle nature of matter were derived.