The fundamental theory for this study， as presented in the introduction and rationale is theoretical. The author cited several well-known theories they put forward. For instance， in the section of introduction， Chomskyan formal linguistics， and the roots of functional linguistics： Prague school， Copenhagen， London school， Michael Holliday， Eggins’ explanation for syntagmatic relations. Furthermore， the rationale of the thesis concentrates on applying SFL tools to the analysis of four English language arts textbook designed to be used in 2nd to 5th grade classroom. The author gives the examples of the rationale for this choice. Such as， researchers and educators’ idea， Ralinscar and Duke’s argument， Relinscar’s foundation， what Schleppegrell founded， and Nathan， long