Starting with black and red checkers to represent rewards and penalties in a coin toss game, Adler patiently explains how to remove red and black pairs that cancel each other out, then switches to positive and negative numerals to represent the scores. Painstaking directions for other games call for maneuvers that are actually adding positive and negative numbers. Number line exercises reinforce and further the concepts. Finally Adler offers directions for making a slide rule and a simple adding machine, then summarizes rules for addition and subtraction of integers which have been demonstrated in the exercises. We can't imagine anyone going through all this without coming out with an intuitive grasp of the concepts -- though admittedly we can't imagine any child going through it on his own at all. In the hands of even a mediocre teacher though Adler's games can be an invaluable aid to learning (and it's easy enough to follow so that all the teacher must provide is the motivation).