"Zone of Proximal Development" (ZPD) is a concept developed by Soviet psychologist Lev Vygotsky. It refers to the range of tasks that an individual can perform with assistance from a more skilled partner, but cannot perform independently. In other words, the ZPD is the gap between what a learner can do alone and what they can do with support from someone more knowledgeable.

According to Vygotsky, the ZPD is a key area of development, as it provides a zone of potential development in which learning can occur. Through interactions with a more skilled partner, learners are able to learn new skills and knowledge that they would not have been able to acquire on their own. This is because the partner provides guidance, support, and feedback, which helps to facilitate the learner's understanding and mastery of new material.

"Scaffolding" is a term used to describe the support and guidance provided by a more skilled partner during the learning process. Scaffolding involves adjusting the level of support provided to the learner, based on their needs and abilities, in order to help them gradually acquire new skills and knowledge. As the learner becomes more competent, the support is gradually removed, until the learner is able to perform the task independently.

The concept of scaffolding is closely related to the ZPD, as it is the process by which learners can bridge the gap between their current level of understanding and their potential for development. By providing appropriate levels of support and guidance, scaffolding helps learners to progress from what they can do alone to what they can do with assistance, until they are able to perform the task independently.