Teaching chess to a home school student can be a challenge. Most parents can teach the moves and maybe a bit of strategy, but then it falls apart. Local chess clubs, co-op chess classes, and private chess coaching are the usual route to continue learning chess. But with some good resources, parents can teach solid chess (and maybe even learn it themselves).
Most chess books are aimed at the experienced player. Even the childish-looking How to Beat Your Dad at Chess is beyond beginning players. I’ve found three books that are excellent for teaching younger players: Chess for Children, Better Chess for Young Players, and Batsford Chess Course. The Chess For Dummies and The Complete Idiot’s Guide to Chess are also decent comprehensive books. Books by Susan Polgar, a female grandmaster, would be excellent for girls.
There are many excellent chess websites that offer articles, puzzles, and ways to play real opponents. One exceptional one for learning is ChessTempo, which dynamically rates players and puzzles so the player is offered puzzles at the appropriate difficulty. A bonus for kids is that you can see your score rise (or fall) as you work, so they continually get feedback on their efforts and can stay motivated to beat the scores of friends and family.
A great free chess tool is Winboard (and the bundled Crafty chess “engine”). Whenever you can’t understand where a game went wrong, playing through the game with analysis turned on is a tremendous help.