Social Development Theory was developed by Soviet psychologist Lev Vygotsky. He believed that social interaction and culture play a key role in cognitive development. Vygotsky focused on how language and interactions with more knowledgeable others in a child's zone of proximal development can aid learning. Some strategies that implement his ideas include scaffolding, reciprocal teaching, and guided instruction where students work together and share problem solving approaches. While it is not specific to any subject, Social Development Theory emphasizes how social and cultural experiences shape thinking skills and understanding through interactions between peers and more experienced individuals.