SFL. Whereas SFL scholars focus on teaching basic genre structures to primary and secondary school students, ESP scholars are focused on teaching Professional and Academic disciplinary genres to University- and graduate-level students. ESP students tend to be more bound to discursive genre subjects, within very particular contexts. ESP focuses on micro-level genres and contexts, whereas SFL focuses on macro-level contexts. Rhetorical Genre Studies (RGS) Rhetorical Genre Studies (a term coined by Aviva Freedman) scholars examine genre as typified social action, as ways of acting based in recurrent social situations. This founding principle for RGS was developed in Carolyn R. Miller's essay "Genre as Social Action," which was published in 1984. In her article, Miller draws on Lloyd Bitzer's notion of exigence as "an imperfection marked by an urgency", that is a condition in the world that serves as an "external cause of discourse." Miller modifies this objective view with Kenneth Burke's notion of "motive" as internal source of human action. Drawing on Alfred Schutz's phenomenological concept of typification, she views situations and exigences as social constructions. Genres are typified ways of responding to recurring social situations. As a consequence genres are not fixed in number and cannot be organized into a taxonomy; rather they are evolving historical constructions that "change, evolve, and decay." A rhetorical approach focuses on genres not as forms but as communicative actions. RGS scholarship has developed beyond Miller's founding definition of genre. Charles Bazerman examined the historical evolution of the experimental article in the sciences and social sciences demonstrating how the major features and variations emerged. He analyzed how the changing forms of the genre and the proliferation of its varieties carried out the activities of those sciences, formed the knowledge of various disciplines, and established criteria about how knowledge should be formulated and evaluated. He also found evidence about how genre expectations influenced the social structure and values of sciences. He then examined how practices of intertextuality and citation developed with modern scientific genres to create more collaborative relations within sciences. Carol Berkenkotter and Thomas Huckin begin with the notion that genre is knowledge foundation, and argue that genres embody communities' knowledge and ways of acting. For Berkenkotter and Huckin, genre becomes a way of navigating social activity. As such, it is dynamic, because the conditions of social activity are always in flux. Recurrence, they claim, involves variation. Berkenkotter and Huckin redefine genre as social