Zone of proximal development

 Zone of proximal development
 The zone of proximal development (sometimes abbreviated ZPD), is the difference between what a learner can do without help and what he or she can do with help. It is a concept developed by Soviet psychologist and social constructivist Lev Vygotsky (1896 - 1934). Vygotsky's often-quoted definition of zone of proximal development presents it as "the distance between the actual developmental level as determined by independent problem solving and the level of potential development as determined through problem solving under adult guidance, or in collaboration with more capable peers."  (from Innovative Learning)

 Wikipedia

 最近接発達領域（ZPD）
最近接発達領域（さいきんせつはったつりょういき）とは、ロシアの心理学者レフ・ヴィゴツキー（L.S. Vygotsky, 1896-1934［写真］）が提唱した、他者（＝なかま）との関係において「ある ことができる（＝わかる）」という行為の水準ないしは領域のことである。

Maximize Learning: Keeping Students in the Zone of Proximal Development