This study seeks to analyze the characteristics found in teachers teaching activities and students core competencies since the introduction of the 2015 curriculum policy. Out of 「KELS 2013」, the 4th(2016) and 6th(2018) data set, the responses of 5,575 10th grade students were analyzed. Descriptive statistics, t-test, ANOVA, and multiple regression methods were used to answer three research questions. The results revealed the following. First, while students’ perception on teachers teaching activities was positive, their perception on teachers’student evaluation method was somewhat low, as it lacked feedback and process focus. Second, students generally recognized the level of their core competencies highly, and the level increased as their grade level went up. Third, with respect to the level of both teachers’instructional activities and student core competencies, the responses of students in special-purpose high schools and autonomous high schools were higher than those of vocational high schools. Finally, teachers’ teaching activities were found to have a statistically significant effect on students core competencies. Based on the findings of the study, a few policy recommendations were presented after discussing the effects of the 2015 curriculum policy on the teacher s teaching and students core competencies.