- Language development begins at birth with crying and progresses through babbling, first words, two-word phrases, and eventually adult-like speech between ages 3-5.
- Key milestones include responding to sounds at 6 months, first words at 12 months, 5-20 word vocabulary at 18 months, and 2-3 word sentences by 24 months.
- By age 3 children can use plurals and past tenses, have a 900-1000 word vocabulary, and understand simple questions. Adult-like speech is achieved by age 5-6.
- Theories of language development include biological, cognitive, social-cultural, and behavioral influences. Piaget saw thought preceding language, while Vygot