Vygotsky's main philosophy is based on social learning. In his theoretical framework, he offers that cognitive development occurs with a combination of dynamics, and that the most important one is social interaction.
In his own words,
"Every function in the child's cultural development appears twice: first, on the social level, and later, on the individual level; first, between people (interpsychological) and then inside the child (intrapsychological). This applies equally to voluntary attention, to logical memory, and to the formation of concepts. All the higher functions originate as actual relationships between individuals." (p57).
Most importantly, Vygotsky's theory presents the zone of proximal development (zpd) as a goal that each student needs to reach for optimal learning, and argues that the best way for a child to learn to get there is through interaction with his MKO peers. The MKO stands for Most Knowledgeable Others, who will help each other cooperatively.
In the modern day classroom, educational theorists such as Susie Miller, Polya and others give special emphasis in social interaction for 21st century learning. Teachers are asked not to sit students in rows, or not facing each other. Instead, they suggest that students are consistently sharing and discussing work, reaching conclusions, setting their own goals, and trying their best in communicate their thinking process both orally and in written form. All this can be traced back to the social learning and cognitive development theories proposed by Vygotsky.