Using the Korea Education Longitudinal Study(KELS) data of 6710 students in 150
schools in Korea, this study investigated how student and teacher factors influence the
trends of middle school students' academic achievement over three years. To
accomodate the nested structure of the data and research questions, the study used the
Hierarchical Linear Modeling(HLM) methods to estimate school effects on academic
achievement. We found that students and schools varied in terms of initial average
academic achievement in 2005(1st grade) and annual growth rate of academic
achievement over three years of middle school. Schools and students both contributed
significantly to academic achievement of middle school students. At each of student and
school levels, average parents' education level, school size, school type, school location,
and school-level teachers' administrative burden had the significant strong effects on
academic achievement. Suggestions and implications of conducting a future study on
teachers' administrative burden on students' academic achievement are also discussed.