This series is now published by McGraw-Hill. We've confirmed we can continue to carry the workbooks, but we're not certain we'll be able to offer answer keys in the future. Availability is currently limited.
The Key-to math books are sets of small, individual workbooks that zero in on specific math concepts. While most math texts try to teach everything needed for a grade level, this series is more specific, covering a few topics in-depth. These topics include english and metric measurment, fractions, decimals, percents and basic algebra and geometry. In the workbooks, the concepts are clearly explained and adequately drilled, while remaining unintimidating to the uninitiated. And they are very reasonably priced.
The consumable workbooks are accompanied by answer keys that include limited notes on the principles being taught. Since this is a student-guided course there is little teacher support, though the instructions and explanations in the worktexts should suffice for most students.
Each topic is covered in 3-10 worktexts. The series is designed for 4th-10th graders, with the idea that you can teach them in any order; however, teaching the more elementary subjects first will make tackling algebra and geometry a lot easier. Students read the text at the beginning of each new section, and then do the work. These aren't flashy workbooks—just black and white text with few pictures—but that simply means there's more room for solid content.
The authors' approach to instruction is pretty straightforward: problem sets are designed to logically work students through the how and the why of each concept without sidetracking them with unnecessary extras. The downside is that there isn't much review other than a practice test at the end of each worktext. A book of reproducible tests for each topic is available from the publisher, but we find these are of little interest to most customers.
Despite the attitude of the publisher and several reviewers, the Key To series is NOT a stand-alone curriculum. While each slim workbook is content-heavy and there are probably enough of them to keep a student supplied for a few years, they just don't have the scope of a full curriculum. The algebra and geometry books are fairly basic and leave out a lot of important elements (the geometry books don't cover proofs or transformations, for example). This series works great for reinforcement of concepts or for remedial work to get a student caught up, but your child will probably be behind in math if he is using Key To as more than a supplement.
These have proven incredibly popular here at Exodus, and we believe the no-nonsense approach of these books make them a great way to reinforce key math principles, especially for kids struggling with those principles (or who need to catch up). We can't stress enough, however, that we highly discourage the use of this series as a complete math curriculum. It just isn't comprehensive enough. As a supplement we think this is one of the best options available.