Promoting higher level thinking

John Mason and friends: ‘Questions and Prompts for Mathematical Thinking’ (ATM publication):http://www.atm.org.uk/Shop/Questions-and-Prompts-for-Mathematical-Thinking/dis002  

The ATM book ‘Thinkers’ is very good too.

Roger Nelsen’s ‘Proofs Without Words’ books: http://www.amazon.co.uk/Proofs-without-Words-Exercises-Classroom/dp/0883857006  

and http://www.amazon.co.uk/Proofs-without-Words-Classroom-Materials/dp/0883857219/ref=pd_bxgy_b_img_y