There are different theories of Language Development. The learning perspective argues that children imitate what they see andhear, and what children learn from punishment and reinforcement. 1The main theorist associated with the learning perspective is B. F. Skinner. Skinner argued that adults shape the speech of children byreinforcing the babbling of infants that sound mostly like words. The 2nativist perspective argues that humans are biologically programming 3to gain knowledge. The main theorist associated with this perspective is Noam Chomsky. Chomsky proposed that all humans have a language acquisition device(LAD). The LAD contains knowledgeof grammatical rules common in all languages. The LAD also allows 4children to understand the rules of however language they are 5listening to. Chomsky also developed the concepts of transformational grammar, surface structure, and deep structure. Transformational grammar is grammar that transforms a sentence. Surface structures are words that are actually written. Deep structureis underlying message or meaning of a sentence. Interactionists argue 6that language development is both biological and social. Interactionists argue that language learning is influenced by thedesire of children to communicate with any others. Interactionists 7argue that " children are born in a powerful brain that matures slowly 8and predisposes them to require new understandings that they are 9motivated to share with others". The main theorist associated with interactionist theory is Lev Vygotsky. Interactionists focus on Vygotsky's model of collaborative learning. Collaborative learning isthe idea that conversations with younger people can help children 10both cognitively and linguistically.