A Parent's Guide to the New Mathematics by Evelyn Sharp, first published in 1964, is a book that explains "New Math" to parents who were not exposed to it in their schooling, but whose children are now taking it, and who find themselves unable to understand their child's math homework.
The book is divided into ten chapters. Chapter 1 provides a brief history of the change of curriculum in the schools and the reason for it. Chapter 10 discusses the impact of these changes on college admissions tests. The remaining eight chapters discuss various "New Math" topics: sets, new arithmetics, number systems, properties of number systems, inequalities, geometry (including topology, non-metric geometry, and different treatments of classical geometry), matrices, and probability.
Sharp is good at explaining these topics to the non-technical reader, and the target audience of the book probably benefited from this treatment.
Probably A Parent's Guide to the New Mathematics is probably not as useful today as it might have been at one time; today's parents, and possibly some grandparents have likely been exposed to these "New Math" concepts themselves. However, the modern reader may still be interested in it for the historical perspective it provides. The history described in chapter 1 may be of interest, as are Sharp's occasional notes about textbooks or other materials being inconsistent with each other or are not as formal as they really should be, suggesting that the quality of the original materials was lower than it should have been (although she does mention that, as of the time of her writing, the quality was improving). It could also be used as a good introduction to the topics discussed in the book.
The rating is based on the book's usefulness today; were I writing 50 years ago, I would give the book a higher rating.