Second language acquisition (language teaching) ; Zweitspracherwerb (Unterricht) ; Foreign language teaching ; Sprachstufung; Language hierarchy; Metalanguage (philosophy of science) ; Unterrichtsgespräch; Classroom dialog ; Metalinguistic awareness; Phonologische Bewusstheit; Phonological awareness; Focus on form (language teaching) ; Sprachbewusstsein; Linguistic awareness