A strong predictor of reading comprehension. Vocabulary size at age 3 can predict reading comprehension at grade 3.
The 30 million word gap… 45,000,000 Words 26,000,000 Words 13,000,000 Words In four years, an average child would accumulate word experience with: Hart, B. & Risley, T. (2003). The early catastrophe: the 30 million word gap by age 3. American Educator (spring) www.aft.org/american_educator