The zone of proximal development refers to the range of abilities an individual can perform with the guidance of an expert, but cannot yet perform on their own.

Developed by psychologist Lev Vygotsky, this learning theory applies whenever an individual has the opportunity to develop new skills. Thus, the term “proximal” refers to those skills that the learner is “close” to mastering.

There are three categories where a learner may fall in terms of their skill set. For learning to take place, it is critical that the expert understands the learner's specific ZPD stage in order to provide the appropriate assistance to boost a learner’s requirement.

Zone 1: Tasks a Learner Cannot Accomplish With Assistance

Tasks that are outside of the learner's ZPD are those that they are unable to complete even with the help of an expert. In this scenario, the expert must decrease the level of difficulty and find tasks that are more appropriate given the learner's skill level.

Zone 2: Tasks a Learner Can Accomplish With Assistance

When a learner is close to mastering a skill, but still needs the guidance of an expert, they are considered to be in their zone of proximal development. In this situation, an expert may use various techniques to help the learner better understand the concepts and skills required to perform a task on their own.

Zone 3: Tasks a Learner Can Accomplish Without Assistance

In this phase, the learner is able to complete tasks independently and has mastered the skill. The learner does not need the help of an expert. When a learner has reached this stage, the expert may increase the task difficulty level in order to find the learner's next ZPD and encourage further learning.

Vygotsky posited that the zone of proximal development is a moving target. By giving tasks that learners cannot quite do easily on their own, but at the same time providing the guidance they need to accomplish them, educators can progressively advance learners’ progress.