Soviet developmental psychologist Lev Vygotsky produced one of the most influential bodies of thought in the history of educational psychology before his death from tuberculosis at the age of 37. His sociocultural theory of development argued that children's higher mental functions — language, reasoning, imagination — emerge through social interaction and are shaped by cultural tools and shared meaning-making. Central to his account of early development is play: Vygotsky argued that imaginative play is the 'leading activity' of the preschool years, a unique space in which children operate at the very top of their developmental potential. He introduced the concept of the 'zone of proximal development' — the gap between what a child can do alone and what they can do with support — and showed that play routinely places children in this zone. Although he published relatively little before his early death in 1934, his ideas, translated and widely disseminated from the 1960s onward, transformed early childhood education worldwide.
