Got this book by Susan Polgar from the library and have found it a great book for the beginner. I have been going over this book with my 3 girls and have already seen an improvement in there understanding of tactics. This is basically a puzzle book with lots of basic puzzles for the improving player. So if you are a beginner or have kids wanting to improve this is well worth the money.

A World Champion's Guide to Chess: Step-by-step instructions for winning chess the Polgar way

You may also want to try Guide To Good Chess, By C.J.S. Purdy (but your kids may or may not like it).