Concordia's Complete Bible Handbook, which is aimed at students. For each book, it talks about
:
*who wrote it and when/where it was written
*how the book is classified (history, poetry, etc.)
*how the book is organized (a high-level outline)
*how the book points to Jesus, and
*some key chapters of the book.
It also discusses background info and pertinent concepts as they come up, and has an overview of the Bible as a whole and the OT and NT, a dictionary, and maps and charts.
There's also a two volume
Bible Companion that is aimed at adults that goes more in depth and engages with competing views. I really love it - it has a ton of good info. Probably a little much for going through with kids that age of yours, but a great reference for adults, to fill in blanks and answer questions.