Vygotsky illustrated the zone of proximal development by drawing a circle to denote the information that a child has mastered and can do without help. For example, a first grader might know how to sound out many words. The zone of proximal development is the area next to the core and includes things a child can do with help. A child who knows how to sound out some words might be able to read more words with the assistance of a parent or teacher. Items outside the zone are things a child can't do, even with help. This might include reading a long and complicated novel or writing a detailed paragraph.
Vygotsky believed that one of the most important things an educator can do is give a child experiences that fit within her zone of proximal development. A kindergarten teacher, for example, might provide children with pens and paper to practice making letters or to ensure that there are plenty of books in the classroom to encourage looking at books or sounding out words. Parents might draw on a child's current interests to help them learn. A third grader who loves insects could learn about evolution by understanding the ways in which different insects fill biological niches.
Scaffolding, according to Vygotsky, is the process through which adults boost children's knowledge within the zone of proximal development. He emphasizes that children learn best when they are challenged to do things they can't yet do on their own, but are "scaffolded" into his understanding. A parent might, for example, help a child sound out a word by emphasizing each individual sound and then encourage the child to combine the sounds. A teacher could scaffold a child into subtraction knowledge by pointing out the correlation between addition and subtraction. She might show the child that two plus two is four, and therefore four minus two is two.
Vygotsky developed the zone of proximal development to emphasize that the type of help a child receives matters, and that no matter how good the help is, it won't work if a child is not ready. An 18-month-old is not yet ready to read, no matter how much help he gets. Conversely, a first grader whose parents only give him easy books to read and who provide no help is less likely to learn than one who is challenged and assisted along the way.