The Book of Roots, published by Memoria Press, is touted as both a "self contained vocabulary course" and a supplementary study for those using Latina Christiana, Memoria Press's Latin curriculum. We've recently given up on the study of Latin as a formal subject in our household, but one of my conditions in allowing that change was that we continue to study roots, so I was curious to see how well the program did in that regard.
At first glance, the book is a little confusing; there is no separate teacher's manual, just some introductory notes at the front to give you an overview and some explanations. This might make it a little tricky if you're used to having your own set of guidelines and reminders, and a little uncomfortable if you have to keep looking at your child's book.
Latina Christiana, the Latin program that The Book of Roots is designed to complement, is suggested for children as young as third grade, and the publisher's recommended ages for The Book of Roots begins there, also, but I really think that this program is much better suited for older children, probably middle school aged at least.
The main reason is the sheer amount of information in the curriculum; not only does each lesson show the primary Latin root word, several secondary roots, and their English derivatives, but the root is shown in its complete form, verbs with four principal parts and nouns with nominative and genitive singular forms. Now, this is a good idea for the reason that many English derivatives come from the fourth principal part of the verb, or the genitive singular of the noun, but it's a lot to digest and remember. A student would also need to have a fairly good grasp of grammar to internalize it, and not all third graders (or even fourth or fifth graders) would be at that point yet.
There's also a great deal to do, in addition to the lessons in the book, if you follow the program to the letter; the notes and introduction suggest having the student complete Drill Worksheets (a reproducible, included in the book) for each word, to keep for reference, memorize a significant number of prefixes and suffixes, identify (and manipulate) the six attributes of the verb (if the word is a verb), and if the word is a noun, identify the gender and gender cause (natural and grammatical). You, the teacher, are encouraged to engage the student in conversation about the derivatives and include them in spelling assignments. All of these are wonderful ideas, but they represent a significant commitment, especially in addition to a full Latin program. Even if this is approached as a stand-alone roots study, it's not simple or designed to be done independently (although a bright, older middle school student or high schooler could probably do it that way).
A Basic Reference in the back of the book provides a quick go-to guide for roots and their derivatives, listed alphabetically by both derivative and Latin root, which would serve as a wonderful review system. But the Advanced Reference that is included, in addition to the Basic one, is what sets this program apart from the rest, in my mind; it provides a thumbnail sketch description of the process of derivativation (say that four times, fast) from Latin, an outline of a few patterns to look for when discerning derivatives (Latin nouns ending in -ficare often have English derivatives that end in -fy, etc.), and a glossary similar to the one in the Basic Reference that has the added bonus of the Latin variants as well as the root words. If you're using the Latina Christiana series, this list is much more extensive than the one in Latina Christiana I, for the purpose of showing explicitly how English derivatives fall into types and patterns.
Here are my impressions after going through this book: if you have a young child studying Latin formally, especially with a program that concentrates on grammar, then this might be a bit of an overload for your student. Over time, a detailed study of Latin itself, with an emphasis on grammar, would likely yield results similar to those achieved by using The Book of Roots. This book serves as a great bridge between English and Latin, filling in the blanks that a student starting the study of Latin somewhat late in their academic career might find useful, and the method and material is much better suited (in my mind) to an older child, as well. A high schooler who has never studied Latin would no doubt benefit from this as a "crash course" in Latin roots, with the Advanced Reference in the back of the book providing enough basic material to give a student a superior vocabulary study.
I have to add that I don't totally agree with the publisher's description of the book, in stand-alone form, as an "ideal standardized test prep course." While an understanding of Latin roots is certainly advantageous when deciphering unknown English derivatives, we can't ignore the importance of having at least a passing knowledge of Greek roots, as well.
But as far as Latin-only root studies go, I think that this book represents the best of the best; not only is it exhaustive in its content, but the added bonus of teaching the how behind the process (through the additional reference in the back) puts it a step above other programs.