A Romance of Many Dimensions
Edwin A. Abbott
This book can be downloaded and read in iBooks on your Mac or iOS device.
This mind-bending early science fiction classic imagines life in a 2-dimensional world. It's a universe populated by lines, squares, and circles, whose perfect flatness creates all new definitions of life, art, and society. Edwin A. Abbott, writing under the pseudonym of "A Square," combines scathing social satire with a brilliant examination on how we all accept our limits of perception, and how much people who transcend these perceptions are often met with resistance.
Best free version
Unlike other free versions, this one has the illustrates.
It's a great novel and I would recommend it to 11-15 year olds