Miss Sharp, whose New Math primers for puzzled parents have had an enthusiastic audience, now turns to considerably less urgent matters--how to prepare a child for first grade through play and games designed to encourage and develop his thinking power. There are those of course who hold with the tabula rasa produced by jolly kindergarten hellraising, considering the achievement-happy parent to be the child's greatest millstone. However, Miss Sharp busily plunges ahead with the larger news from developmental psychology labs--the work of Piaget, Brunner, Karpus and British Infant Schools. A most interesting section this is, affording the reader a pleasing sense of recognition when all the bag of tricks used on educational TV--glasses of colored water, equal dollops of molding clay, sequential figures--are explained. Miss Sharp concludes with a group of games firmly labeled with purpose (conserving quantity, experience in classification, etc.) for home prodding. But we bet these rather grim games will never beat cake-division for conserving quantity nor Old Maid for instant classification.