The purpose of this study is to analyze influence of teachers' variables on student
achievement. In particular, various activities of teachers in order to enhance professionality
which have been neglected by previous studies are taken into accounts. And it tries to
investigate the impact of teachers' professionality development activities on their students
achievement. In this analysis, we used Trends in International Mathematics and Science
Study 2007 by making use of hierarchical linear modeling. TIMSS 2007 consists of detailed
questions about teacher, especially teachers' activities of professionality development.
The results, first, show teacher-level variables explain 29.9% of the variance in student
achievement. This means student achievements can differ across teachers whom students
belong to. Second, in the teacher characteristic variables, gender variable is statistically
significant in explaining students' mathematics achievement gap. The factors such as final
degree or a college major, instruction readiness are not statistically significant. Third, among
variables corresponding to the teachers' efforts to enhance teacher professionality,
communicating with colleague teachers on the preparing teaching materials is significant
variable explaining student achievement. In contrast, the frequency of participating in teacher
professionality development programs or in-service does not explain their students'
mathematics achievement gap with a statistical significance.