The work in this domain focuses on the knowledge, comprehension, and application of the major theories and research in the field of second language acquisition (SLA). The first standard in this domain (i.e., Standard 1.a.) involves systematically analyzing language. In particular, my research focuses on a cross-linguistic analysis of English and Japanese from a phonological and from a pragmatic perspective. The second standard in this domain (i.e., Standard 1.b.) involves understanding the language acquisition process in learners. My research focuses on investigating a particular type of task (i.e., 4/3/2) on speaking fluency and analyzing the development of a particular language feature (i.e., auxiliary verb usage) in a single learner over time.