Final answer:
Vygotsky's central concept in his theory is mediated learning. According to Vygotsky, children learn the meanings of words from their surrounding culture.
Step-by-step explanation:
Vygotsky's central concept in his theory is mediated learning. According to Vygotsky, children do not independently construct the definitions of words they learn, but instead acquire the meanings that their surrounding culture ascribes to those words. This idea emphasizes the role of social and cultural factors in language development and learning.