In Korean education, as in any language education system, there are complicated grammatical and contextual concepts requiring in depth explanations, for example, the difference between tense and aspect, and between subject and topic. It is very challenging for teachers to respond effectively to students' question on precise meanings and usage in context when even linguists have not resolved yet these issues. In this paper, I systemize precisely 'subject' and 'topic' in current Korean usage, and offer a method to explain the meaning and function of the particles ‘-이/가’and ‘-은/는’. I also propose that the concept of 'subject' and 'topic' should be viewed from entirely different perspectives. In the last few decades "subject' has been studied in syntax as a significant constituent acting as an agent with the predicate of a sentence. However, strictly speaking, 'topic' is not a notion of syntactic structure but of pragmatic usage in practical conversation contexts. Therefore, the particle ‘-이/가’ should be dealt with not only syntactically but also from a pragmatic perspective. The particle ‘-이/가’ is used for the maker of the subject at sentence level but at the pragmatics level it definitely has the function of 'focus (comment, new information)'. Also, the particle ‘-은/는’ is not a case maker at sentence level but a special particle with the meaning of 'contrast'. At the pragmatic level, except as a maker of 'contrast', the particle ‘-은/는’ is the topic marker (given, old information)' that has been identified between the speaker and the hearer with appropriate conditions in some contexts. In conclusion, in Korean language education, the notions 'subject' and 'topic' should be taught as different conceptions of different domains, and the particles ‘-이(-i)/가(ga)’ and ‘-은(eun)/는(neun)’ should also be considered at both the syntax and pragmatics levels. The particle ‘-이/가’ is a 'focus' marker (comment, new information)' as well as a subject marker. The particle ‘-은/는’ is a special particle with the meaning of 'contrast' in syntax and also the marker of 'topic(given, old information)' in pragmatics.