Norbert Pautner 
Tangram Teasers Book 

Based on the best-selling Book-in-a-Box kits, the Tangram Teasers book will challenge you to first solve the puzzle by creating the shape shown, but then change it into the new shape in only the set number of moves indicated. Just when you thought tangrams were easy, they got harder. But there are three levels of difficulty and so you can start off gently, and then get more and more teased! Try the tangram challenge. But watch outtangrams are addictive!