Sideways Stories from Wayside School, by Louis Sachar. (Avon Books, Humorous episodes from the classroom on the thirtieth floor of Wayside School, which was accidentally built sideways with one classroom on each story.
Sideways Stories from Wayside School: Louis Sachar. An incredibly quirky children's book. A quick, easy read that emphasized, to me, the importance of imagination making the world a place of wonder for children.