Zone of proximal development

The gap between the learner's current or actual level of development determined by indpedendent problem solving and the learner's emerging or potential level of development.

This idea is very similar to Jim Cummins idea of information plus one or i+1. Learners cannot build new knowledge without first having a framework or prior learning foundation. Vygostsky says that learners' are generally not able to bridge a large gap of learning without some cognitively related prior knowledge to 'hang' the new information upon.