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.