English as a second language; ESL; TESOL ; Unterbrechung (Diskursanalyse) ; Interruption (conversational analysis) ; Dialogsteuerung; Alternation (pragm.) ; Sprecherwechsel ; Institutional communication ; Ingroup communication ; Classroom communication; Instructional communication ; Teacher talk; Teacher's language ; Second language acquisition (pragm.) ; Zweitspracherwerb (pragm.) ; Interactionist hypothesis (second language acquisition) ; Conversational analysis (second language acquisition) ; English