Glottodidaktik; Lehrforschung; Pädagogische Linguistik; Pedagogical linguistics; Language teaching research ; Triggering (language acquisition) ; Language exposure (language acquisition) ; Input hypothesis; Input (language acquisition) ; Interimsgrammatik (Spracherwerb) ; Lernervarietät (Spracherwerb) ; Learner variety (language acquisition) ; Interlanguage (language acquisition) ; Critical period (second language acquisition) ; Alter (Einfluss auf Zweitspracherwerb) ; Age (influence on second language acquisition) ; Ultimate attainment (second language acquisition) ; Near-native competence (second language acquisition) ; AoA; Age of acquisition (second language acquisition) ; Sensitive period (second language acquisition)