John Abbott 
The Improvisation Book [EPUB ebook] 

A practical guide to conducting improvisation sessions, for teachers, directors and workshop leaders.
The Improvisation Book takes you step-by-step, session-by-session through a graded series of improvisation exercises. Starting with the very first class, it adds a new element at each stage until even the most inhibited students have gained a full vocabulary of improvisational techniques.
'a veritable treasure trove… Abbott's book is of real value in the training of actors; I'm enthused and excited about putting it into practice' – Reviews Gate.com
'distils a lifetime of experience and is set out logically and practically so that would-be actors can build skills from the very simple to the remarkably complex' – British Theatre Guide