English as a second language; ESL; TESOL ; Glottodidaktik; Lehrforschung; Pädagogische Linguistik; Pedagogical linguistics; Language teaching research ; Silence ; Classroom communication; Instructional communication ; Vietnamese ; Filipino; Philippinisch ; Japanese ; Korean ; Mandarin; Kantonesisch; Cantonese; Putonghua; Sinitic; Hakka; Yue; Chinese