"Very good," says Magnus, proudly. He's thinking through solutions. He's actually picked up some books from the library, too, about the hand shapes that are hard for babies in the same way that certain sounds are hard for babies. Of course, Sunny is a miracle genius baby who is great at all sorts of communication, but she still has those cute little baby hands.

He decides the best solution is to sign it at her again, much more slowly, so she can see the way he forms a K in the middle of the sign for 'brother,' instead of pointing in the usual way, and then transitions it into the sign for 'book.'