Conclusion
Korean students are excellent linguistic chameleons! They are very good at mimicking accents and words immediately after hearing them, but this does not mean that they have achieved or mastered the aspect of language being taught. It is common to have students who appear to have mastered skills in one lesson and seem never to have heard of them in the next lesson. It usually takes a lot more repetition than initially anticipated for students to demonstrate genuine progress and knowledge so teachers should not be scared to spend more than one week on new language concepts.