Mary Haight 
The Snake and the Fox [PDF ebook] 
An Introduction to Logic

The Snake and the Fox is a highly imaginative and fun way to learn logic. Mary Haight»s characters guide you through an elaborate tale of how logic works. This book features the Snake and the Fox, Granny, Gussie and the Newts, Ren^De Descartes and Miss Nightingale, along with a huge supporting cast of humans, devils and sausage machines.
For anyone coming to logic for the first time, this is the best place to start. Mary Haight makes logic easy and fun — she asks the reader questions, and uses words instead of logic symbols with amusing pictures and characters to help them.
This book teaches all the basics the reader needs to know about logic (how arguments work, sound, valid reasoning, truth tables, Venn diagrams etc) in a truly enjoyable and innovative way. Anyone teaching themselves logic, or learning it on a course is bound to benefit fromthis original and intriguing book.