1. Principles of second language acquisition can help teachers by showing that children learn language through imitation, exposure, and paying attention to creative errors. The order children acquire language structures and their ability to learn without direct instruction also inform teaching.
2. The critical period hypothesis suggests that exposure to language early in life is important for fluency. Recasting allows adults to implicitly correct grammatical errors and expand children's utterances to model correct language.
3. Motherese or caretaker speech that adjusts language to a child's level helps their expressive abilities develop rapidly. Implicit recasts when a child's language contains errors also guide language learning without direct criticism.