DaF; Deutsch als Zweitsprache; German as a second language; DaZ; German as a foreign language ; Sociology of translation; Language and social studies ; Play (function in language acquisition) ; Spracherwerb und neurologische Entwicklung; Language acquisition and neurological development; Sprache und Denken (Ontogenese) ; Language and thought (ontogenesis) ; Cognitive development; Language acquisition and cognitive development ; Second language acquisition in children; Kindlicher Zweitspracherwerb; Child second language acquisition ; German