The concept of 'Scaffolding' (often referenced as Instructional Scaffolding) was introduced into educational psychology with respect to the social construction of knowledge by which theorist?

According to Vygotsky, the most developmentally significant form of play is:

Ramesh, an 8-year-old child, mostly interacts with his younger, less mature siblings. According to Lev Vygotsky's socio-cultural theory, what is the most likely result of this interaction?