These books in The Medieval World series, published by Crabtree Publishing Company, serve myriad purposes. For the intended reading age, 9-12, they present medieval life--very confusing to our contemporary conventions--in a perfectly understandable fashion. For that age range, I could not recommend these books higher.
Yet they also serve a purpose that the publisher may not have intended, and that is for the casual researcher of medieval life.
There are accessible texts for the casual researcher, this is true, but none of them--that I've seen, that is, and to their detriment--contain simple explanations and diagrams. For example, in this book, there is a two-page full-color drawing of a medieval manor, and it gives a better bird's eye view than any scholarly text I've come across.
Every page in the book, for that matter, is presented in full color, the pages colored to resemble parchment, and the illustrations done to wonderfully evoke the period.
I've read a number of books on the Middle Ages, but until I came across this one, I never really had a good image of a medieval manor: where the "peasants" lived, where the church was situated, where the mill was and how it worked (yes, there's a diagram on how the mill works, and what the components of the mill are called), who performed some of the essential duties of the Lord of the Manor (who really couldn't be troubled) and many others.
If you're a writer, and you're looking for simple information on what medieval life looked like, this series of books can't be beat.