The first time I heard of Vygotsky was my freshman year of college in my Educational Psychology class. We spent large amounts of time discussing the difference between Piaget and Vygotsky and the way they beleive learning happens for students. Vygotsky's theory of zone of proximal development always seemed very straight-forward for me. That is until I read our article for class. Even so there are some things that seem to be the basics for ZPD.
To me the basic idea is that every child can learn as long as its within their knowledge base to do so. The process of measuring a students ability not only measures what they already know, but what they are capable of knowing in the future. However what children are capable of knowing is not always reached alone. Students need scaffolding from their teachers, family, friends, and peers to help them reach what is in their "zone of proximal development".
This idea to me as a future teacher seems broad but reasonable for classroom understanding. I think its particularly important for teachers to know where each of their students stands on a certain subject, whether it be math, science, or reading. In doing so they are able to develop lessons that extend their zone of proximal development. This can happen in one day or over a long period of time. One day a student might need many sources of scaffolding for an activity, and by the end of the week are sucessfully conpleted the same activity by themselves. From what I understand about Vygotsky this makes the former new information now something the students know, and then makes room for more information that they can recieve scaffolding on. A process that can be repeated over and over.
For example my freshman year ZDP was something I have never even heard of, but as it was introduced to me it became something that was in my own zone of proximal development. Over time through scaffolding of my teacher, my peers, and other resources it has now become something I can describe.