Sign Language for little ones

So with Carolyn learning sign language, she often uses her hands to talk to the kids and they know many signs.  Even Gwena, that can make the sign for Mama, Dada and does pray.  Mama is hand open below the mouth and Dad is hand open at the forehead (she does her's on top of her head)  She uses the verbal words of "mama" and "Dada" when she does the sign.  Little babies are so intelligent, I swear we do not give them enough credit.