Guitar Method for Young Beginners - Book 1 - This book is used for beginner players who are aged between 5 and 6.
Progressive Guitar for Young Beginners is a carefully graded, lesson-by-lesson learning method for the younger student using very easy arrangements of over 20 favourite children's songs. Purchase the paperback, not the kindle version.
Hal Leonard Guitar for Kids - This book is for beginner players aged 7-10
Guitar for Kids is a fun, easy course, that teaches classic, popular songs such as "Yellow Submarine" (The Beatles), "I'm a Believer" (Neil Diamond, The Monkees, Smash Mouth - Shrek), Surfin' USA (The Beach Boys) and Hound Dog (Elvis Presley)
Hal Leonard Guitar Method: Complete Edition - This is three books in one and will guide beginner players aged 10 and up. If you would prefer to buy the books separately, you can get Book 1, Book 2 and Book 3.
If you're left handed, you can also get Book 1 Left Handed edition.
This is a great, easy to follow method that gets into songs right away, and focusses on playing, while still giving a solid musical education that can set someone up for years of musical enjoyment.