Thirty million: In the world of early-childhood education that number represents the supposed gap between middle- and low-income children in the number of words heard by the time they are three years old.
The original study that generated that 30 million number is now 20 years old. The number has frequently been used to explain some children’s more limited vocabulary and the academic disadvantage they face because of it.
According to Education Week, subsequent studies have shown that the word gap is really smaller, perhaps closer to 11 million words, and that the entire language acquisition landscape is really more complicated than many summaries of the original study would suggest. Read more