So B. It by Sarah Weeks

Twelve year old Heidi has lived all her life in one apartment, with her mother and their next-door neighbor, Bernie. Well, technically it's two apartments; Bernie has her own, but there's a door that connects hers to Heidi's, and it's always open.

Bernie is a big part of Heidi's life: she took care of Heidi when she was a baby, teaches her schoolwork, and in many ways is the mother that Heidi's real mother cannot be.

You see, Mama - or Precious, as Bernie calls her - has a hard time remembering things, or learning how to do them, or even talking. Bernie and Heidi keep a list and Mama has only twenty-three words that she says: things like good and hot and Heidi. But there's one word that only Mama says, and she says it often: soof.

It drives Heidi crazy, that she doesn't know what Mama's word means. It isn't in the M.B.F - Man's Best Friend, otherwise known as the big Webster's Dictionary - and neither Heidi nor Bernie have any idea what it could be. And of course, Mama can't tell them - in fact, she seems to get more and more agitated whenever Heidi asks.

But when Heidi finds an old camera in a drawer and gets the pictures developed, suddenly she has more questions - and the chance at a lot of answers.