This document summarizes key aspects of language acquisition in young children based on theories and research. It discusses stages of development for areas like telegraphic speech, order of morpheme acquisition, negation, questions, and restructuring. Principles of second language acquisition can help teachers understand similarities and differences between first and second language learning. While age is a factor, motivation and learning conditions also influence language development. Adult speech is modified, or "motherese", when talking to children, using simpler structures and repetition to aid comprehension.