Glottodidaktik; Lehrforschung; Pädagogische Linguistik; Pedagogical linguistics; Language teaching research ; Lehrmaterial; Teaching material ; Techniques (in research) ; Research techniques ; Classroom communication; Instructional communication ; Second language acquisition (pragm.) ; Zweitspracherwerb (pragm.) ; Interactionist hypothesis (second language acquisition) ; Conversational analysis (second language acquisition)