Don't You Dare Read This, Mrs. Dunphrey by Margaret Peterson Haddix

Tish has to write in a journal for part of her grade in a high school class. Tish has a bad attitude towards school, life, people around her, excepting of course, her family and close friends. At the beginning of each journal entry, Tish writes, "Don't you dare read this, Miss Dunphrey", this allowing her to spill her guts about the rotten situation her family is in, what friends have done, what she's done, etc. She only lets Miss Dunphrey read a few. Miss Dunphrey mildly comments on the length or the number of entries per week, ignoring the obvious pleas for help. Through out the book, Tish's home life goes from bad to worse as her father comes in and out, nice at first, then abusive. When her mother leaves to go after her father, Tish's life goes into a living hell. Faced with feeding her and her brother, paying bills and trying to look like a normal family, Tish pours this all out into a journal, while sweet, innocent Miss Dunphrey completely ignores her cries for help. Finally, Tish allows her naive stupid teacher to read her entries and Tish and her brother are shipped off to a set of grandparents they've never met.