It seems like in the past couple of weeks, a switch has flipped in Alex’s head, and suddenly he’s a human being. He just made a huge leap in sort of understanding.
Anyway, without further ado, I present to you videographic evidence:
Alex saying “mama”:
Alex doing “bye bye”:
Alex doing “so big”:
Alex signing “more”:
Other signs that he knows include “milk” and “all done”, and he understands “book” and “train”, but doesn’t do them himself.