Vygotsky's social constructivism theory emphasizes that knowledge is socially constructed through interactions. The zone of proximal development (ZPD) refers to the range of tasks a child can accomplish with guidance either from peers or instructors. Within the ZPD, the lower limit is what a child can do alone and the upper limit is what they can do with help. Scaffolding refers to instructors adjusting their support based on a child's performance level, providing less help when in the upper ZPD range. Vygotsky also believed private speech and language shape thought development in children.