Vygotsky differed from Piaget in that he considered development after age 2 as, at least partially determined by language. He believed that egocentric speech serves the function of self-guidance, and eventually becomes internalized. It is only spoken aloud because the child has not yet learned how to internalize it. He found that egocentric speech decreased when the child's feeling of being understood diminished, as when there was no listener or the listener was occupied with other matters. These ideas, while intriguing, have never been adequately researched, so it is difficult to evaluate their significance.
While there can be wide variation of activities and content in a Vygotskian classroom, four principles always apply:
1. Learning and development is a social, collaborative activity
2. The Zone of Proximal Development can serve as a guide for curricular and lesson planning
3. Classroom activity should be reality-based and applicable to the real world
4. Learning extends to the home and other out-of-school environments and activities and all learning situations should be related.