English as a second language; ESL; TESOL ; Register (language teaching) ; Sampling; Language corpus; Sprachkorpus; Datensammlung; Data collection; Textkorpus (method.) ; Text corpus (method.) ; Corpus linguistics ; Metalinguistic awareness; Phonologische Bewusstheit; Phonological awareness; Focus on form (language teaching) ; Sprachbewusstsein; Linguistic awareness ; Interimsgrammatik (Spracherwerb) ; Lernervarietät (Spracherwerb) ; Learner variety (language acquisition) ; Interlanguage (language acquisition) ; English