This paper aims to make a tool for developing teaching ability of Korean language teachers in foreign countries, centered on Korean Schools in the U.S.. I make a diagnosis of two problems of Korean Schools based on the educational situation of Korean Schools. Those are (1) comprehension and memory centered teaching caused by the teacher’s educational experiences, (2) ineffective classroom culture. For reforming the problems and improving their teaching methods, I develop three self assessment tools, by modifying the self-study of teaching practice methods in Samaras & Freese(2006), Ruth Wajnryb(1992) and Borich Gray(2003). Those are (1) a personal history self-study method in which a teacher record and reflect his/her educational-related life experiences, (2) a developmental portfolio self-study method in which a teacher makes a journal of a problem child and classroom cultures.