Let’s think back to when you were 1 year old, then 2 years old, then 3, and then 4. Do you remember being 4? Even if you don’t, we’re sure the adults around you remember. You understood just about everything everyone said, and if you didn’t understand an idiom, you asked, and it was explained. Every word you learned, you watched people’s mouths on how to form the sounds. You did this for...