Everything you need to understand or teach So B It by Sarah Weeks.
So B. It is about Heidi, a 12-year-old girl whose mother is mentally disabled and can only speak 23 words —including a made-up word, “soof”. Bernadette, their neighbor, takes care of both of them. The story is about Heidi’s quest to find out what “soof” means by traveling across the country led by the clues left on an old roll of film.