The Zone of Proximal Development takes into consideration each student's strengths, weaknesses, and preferences. The ZPD is the stage at which the student is considered "instructional." Compare this to an independent stage, in which the child has already mastered all of the skills being presented and can apply those skills without teacher or peer assistance and to the frustration stage, in which the skills are too difficult for the child to complete with an appropriate amount of peer or teacher assistance. At the ZPD, the child is ready to learn a new skill through teacher modeling, several examples of guided practice, repeated independent practice, and then assessment and follow-up.
Scaffolding is essential, as students enter preschool with varying degrees of knowledge about important concepts such as shapes, colors, numbers, alphabet knowledge, rhyming, etc. Some students may arrive already counting to 100 and recognizing numerals through 20, whereas others do not know how to count nor do they recognize any numbers represented in written form. The same lesson will not meet the instructional needs of both students, as they both are at very different levels of development (ZPD). Therefore, the lesson can be scaffolded to allow for instructional opportunities that will leave each child with a successful learning experience. For example, the child who can already count and recognize numbers could work on counting groups of objects and writing the numeral that represents the group, while the child who does not have 1:1 correspondence or number sense would learn to count orally to 10, learning the names of the numbers and their order.
Reading is another great example of where the ZPD and Scaffolding is important in the preschool classroom. One child may not have had many experience with print, and not know how to hold a book, to retell a story, or recognize any letters of the alphabet. On the other hand, there may be a student who can sing the ABCs, recognize the alphabet, know letter sounds and maybe even know some sight words. The first child would be frustrated by a lesson on blending 3 letters together to read a word, while the second child would be completely bored if asked to sit through "letter of the week" lessons. Therefore, the lessons would be scaffolded to allow each child to work at their ZPD to learn something new that is appropriate to their current level of knowledge.