http://www.rakuten.com/prod/complete-book-of-chess-strategy/30322920.html?listingId=226355342&s_kwcid=
This isn't too advance, but may even help some mid level players with some things too.
If you both go through it together, I promise BOTH of you will see improvevment, with effort of course.
It should be fun. If she has not yet beat you get this one:
How to beat your daddy at chess
Chess Made Easy by CJS Purdy & G Koshnitsky.
Its a small (60 page) booklet been in print since 1942 & still available today. Its easy to read, very thorough & claims it will get you playing in 2 hours.
Perfect for a child, it will get him started & up to club level.
I have a 1st edition & it is still relevant although there have been a number of updates over the years. You can find it online, ebay is probably cheapest, over here it i
s selling for about $15 (Australian)
Any books by Murray Chandler is great for kids.
https://www.google.com/search?q=murray+chandler+books&rlz=1C1CHMO_enAU520AU520&oq=murray+chandler&aqs=chrome.2.69i57j0l5.8920j0j7&sourceid=chrome&espv=210&es_sm=93&ie=UTF-8
"Logical Chess: Move by Move" by Chernev
Written for adults, but uses simple language that children could understand. The book is instructive, though the openings it shows are rather old (e.g. Italian Game, QGD - this might actually be good as it could be hard to teach an 8 year old Najdorf theory!). You could go over each of the games with him - it's quality bonding time!
Also a book for basic strategy, written "for kids": Winnning chess strategy for kids. I have the book, and though I havn't read it cover to cover, just the first 50 pages, I liked it.
I'm looking to get a chess book for my 8 year old son, a basic strategy book, any recommendations?