We have Book C, so I'll describe that one.  Books A and B are probably similar.  There are 12 word lists in the whole book with 8-10 words in each list.  Each word list has 3 exercises that help the student to learn the meanings of the words.  Once two words lists have been learned, there is a crossword puzzle. 

The word list (containing 8-10 words) is contained on one page.  It has the definitions and some illustrations.  The part of speech is listed as is at least one definition of the word, but often more than one meaning of a word is presented.  A sentence containing the word is also included so that the student can hear the word in its proper context. 

The first exercise is a list of 16 true or false statements which focus on the meanings of the words. 

The second exercise requires the student to read a sentence. Then to focus on the underlined words.  The underlined words are a definition of one of the list words.  Then the student is to rewrite the sentence substituting the list word for the underlined words. 

The third exercise is quite fun.  The student is asked a riddle and  must perform the exercise to get the answer.  The student is given the definitions of the words and a grid is provided in which to write the list words.  When the grid is filled in, the answer to the riddle can be read.  These are cute little riddles--often a play on words. 

If one exercise a day is completed, there is only about enough work for 42 days.  That doesn't seem like a whole lot to me.  But plenty of words are learned.

I've not seen books A and B, but Book C should probably be fine for a average 8 year old.  However, writing out the whole sentences in the second exercise could be too much writing for a child of that age.  We remedied that by just writing the list word.  I think that Book C is a little too easy for a 4th grader, but that's just my opinion.

This is a very popular series.  In fact I ordered Level 1 for my daughter after she finished Book C.  However, I went ahead and sold it since I didn't care for the format.  The main thing that bothered me was that the word list didn't contain the meanings.  Each vocabulary word had to be looked up in the glossary in the back of the book.  This isn't a big deal, but my daughter reminds herself throughout the week of the word meanings, and I suspected that she would be frustrated with having to continually look up the vocabulary words in the glossary in back.  The lettering also has a dated look to it.  (yes, I know, a very minor point) 

This is what the Level 1 that I sold contained.  There were 10 chapters.  Each chapter consisted of 3 Lessons and one crossword puzzle.  Each Lesson contained 4 exercises. 

At the beginning of each Lesson is a word list consisting of about 12 words.  The student is to look these up in the glossary at the back of the book. 

Exercise A in each lesson gives a phrase using a vocabulary word and then the student is to choose which of the 4 choices has the same meaning as the vocabulary word. 

In Exercise B each vocabulary word is used in 4 sentences.  The student is to choose the sentence in which the vocabulary word is used incorrectly. 

In Exercise C a sentence is given.  The student is to replace the italicized phrase with the correct vocabulary word. 

In Exercise D a phrase is given and the student is supposed to put the correct vocabulary word (that describes the phrase) in horizontal boxes.  When all the horizontal rows of boxes are filled in, there is a column of boxes running vertically that supply a message. 

The crossword puzzle that is at the end of each chapter (which includes about 36 words) is a quick review.

Basically, that's how the Worldly Wise, Level 1, is set up. 

Oh, don't let me forget the actual Wordly Wise section.  At the end of each lesson there is a short (about 1/3 of a page) section concerning word histories and commonly confused words.

From what I understand, Books 7-9 have a slightly different format. 
 

I have books 1 and 3.  There are 20 Lessons in each of these books.  After 4 lessons there is a word puzzle or crossword puzzle for review.  There are 5 exercises in each of the 20 lessons. 

To describe each lesson, it starts with a Word list of 15 words.  The part of speech, definition, and sentence with list word in it are all given.

Exercise A is called Finding Meanings.  The student is to pick two phrases from a total of four phrases and make a sentence that is true.  For example:  a) a gradual increase over time.  b) Contamination is c) Conservation is  d) contact with something harmful.  Out of those four, the student is supposed to choose two and write the sentence on the line provided.

Exercise B is called Just the Right Word.  Here the student is given a sentence with a phrase that is italicized.  The student is to replace the italicized words with a list word.

Exercise C is called Applying Meanings.  Here the student is to read a question and then circle all that apply.  For example:  Which of the following would diminish one's freedom?  a) being held captive b) having one's driver's license taken away c) joining the navy d) being released from prison.

Exercise D is called Word Relationships.  There is a group of four words given to the student.  Out of those four the student is supposed to choose the two words that are either antonyms or synonyms and then identify their relationship (synonym or antonym).

Now comes the difficult one!  It's Exercise E.  The student reads a page-long essay that contains all 15 of the words.  Usually it's on a fairly decent topic.  Some topics included are Sequoyah, Trojan Horse, Bedouins, Marco Polo, Yani (a painter), blimps, etc.  Once the student is done reading the essay, there are 15 questions to answer.  This exercise is really causes a student to think--use the ol' noggin. 

I think that Exercise E is a little too difficult, though.  Here's the exact instructions.  "Answer each of the following questions in a sentence.  If a question does not contain a vocabulary word, use a vocabulary word in your answer.  Use each word only once.  Questions and answers will then contain all fifteen words (or forms of the words) from this lesson's word list."  Sounds easy, but it's not.  It easy to use the wrong list word in the sentence and then have to go back and redo it when you find out that you need to use that list word later.  Plus the student has to keep a running record of which words have been used in questions and which have already been used to answer questions.  To me, this isn't worth the effort.  So I have my two students do their best to use any vocabulary word in each sentence while making sure to answer the question correctly.  This eliminates the need to keep a running tally of which vocabulary words have or haven't been used yet, and the student still gets plenty of practice composing a sentence using a list word.  Please don't misunderstand; I think that Exercise E is very valuable, but, for us, it works much better to put our own little twist on it.

So there are five exercises per lesson, then once in a while there is the word puzzle.  This works fine for scheduling.  For four weeks my students can do 1 Lesson (5 Exercises), and then have a whole week to do the word puzzle/crossword puzzle.  However, my two children do Exercises A and B on Monday; Exercises C and D on Tuesday; and then Exercises E is spread over 3 days.  Trying to do all of Exercise E on one day is just too much work, I feel.  Then the word puzzle can be done during the fifth week with a couple of days for catch up if we have missed a day or two of school here or there.

With each lesson that is a Wordly Wise section that goes into the origins of words, describing why the word came into being and/or what language it comes from.

I particularly like the fact that the word list includes the definitions of the words.  This is much easier for the students since they won't have to flip back and forth between the lesson and the glossary in the back (as in Wordly Wise) if they need to be reminded of the meaning of a word.

The catalog indicates that Books 6-9 are more challenging and have a different format, though they are probably similar.

UPDATE:  My son is using Book 6 right now.  Things have changed a bit with Book 6. Here's what each Exercise includes:

Exercise A is called Understanding Meanings. The student reads 15 sentences.  If the vocabulary word is used correctly, do nothing.  If the vocabulary word is used incorrectly, then write a sentence using the vocabulary word correctly.

Exercise B is called Using Words.  He is given 8 vocabulary words.  For each vocabulary word, there are three sentences with one word missing.  The student is supposed to decide if the vocabulary word will fit the context of the sentence.

Exercise C is called called Synonyms, Antonyms, Analogies.  It is similar to Exercise D described above but also includes analogies.

Exercise D is called Images of Words.  The student is given a vocabulary word and then must decide if it is used properly in the three sentences below the word.  It could be all of them or none of them.  Tricky.

Exercise E is the same as above.
 

The system outlined in the book would be useful for about grades 8-12, but the word and root lists can be useful anytime that your student is learning Latin and Greek roots. 

Good reference.  Low price.  A few other vocabulary books are listed at that site, also.

The Princeton Review Word Smart SAT Hit Parade (Audio)

Word Smart Genius Edition:  How to Build a Phenomenal Vocabulary (Audio) 

Word Smart Genius Edition:  How to Build an Even More Phenomenal Vocabulary (Audio) 

The Princeton Review Word Smart Junior:  Build a Straight 'A' Vocabulary for Grades 6-8 (Paperback)

Word Smart Junior II : More Straight-A Vocabulary for Grades 6-8

Illustrated Word Smart : A Visual Vocabulary Builder

More Illustrated Word Smart

Word Smart for Business : Cultivating a Six-Figure Vocabulary

SAT Verbal Velocity

500 SAT Words, and How To Remember Them Forever!

Kaplan Word Power (750 must-know words, 55 practice quizzes)

Peterson's SAT Word Flash 2002

Up Your Score 2001-2002: The Underground Guide to the SAT