The Zone of Proximal Development (ZPD) is a concept from psychologist Lev Vygotsky, describing the difference between what a learner can do independently and what they can do with guided support. In other words, it’s the range of skill or knowledge that is just beyond a person’s current ability, but can be achieved with appropriate help. The ZPD represents an optimal learning zone – within it, tasks are not so easy that no growth occurs, but not so hard that the learner is frustrated or incapable.
In speech-language therapy, SLPs consciously work within a client’s ZPD by providing “scaffolding.” For example, if a child can’t quite use plural forms correctly on their own, the SLP might first provide a model or partial cue; with this support, the child succeeds, and over time the scaffold is removed as the child internalizes the skill. The ZPD concept also underpins dynamic assessment, where an SLP might test how a child learns with mediation (to see potential, not just static performance).
Vygotsky, L. S. (1978). Mind in Society: The Development of Higher Psychological Processes. Harvard University Press.
Gutiérrez‑Clellen, V. F., & Peña, E. D. (2001). Dynamic assessment of diverse children: A tutorial. Language, Speech, and Hearing Services in Schools, 32(4), 212–224. Link
