Today, L.S. Vygotsky's concept of a 'zone of proximal development' (ZPD) is often used to just mean best practices in early years teaching, like scaffolding. But in his original theory, the zones linked age periods distinguished by age-specific neoformations -- one of which was the formation of concepts at adolescence. So Vygotsky rejected Stern's idea that early years already had the wherewithal of adult concepts and affirmed the age-specific quality of child thinking instead. He demonstrated this through two ingenious 'name games'. In this paper, with the help of two Korean children, we will replicate the name games and use one game to study the difference between Vygotsky's 'Crisis at Three' and the 'Crisis at Seven'. We describe the differences from the systemic-functional perspective of Ruqaiya Hasan and Michael Halliday. In this way, we hope to restore a diagnostic function to Vygotsky's ZPD.