Matilda by Roald Dahl

Matilda is a little girl who is far too good to be true. At age five-and-a-half she's knocking off double-digit multiplication problems and blitz-reading Dickens. Even more remarkably, her classmates love her even though she's a super-nerd and the teacher's pet. But everything is not perfect in Matilda's world... For starters she has two of the most idiotic, self-centered parents who ever lived. Then there's the large, busty nightmare of a school principal, Miss ("The") Trunchbull, a former hammer-throwing champion who flings children at will, and is approximately as sympathetic as a bulldozer. Fortunately for Matilda, she has the inner resources to deal with such annoyances: astonishing intelligence, saintly patience, and an innate predilection for revenge.