teaching chess to kids?

i want to teach my 7 and 8 year olds how to play chess. we tried it the other night and they wre enjoying it for awhile but became frustrated with all the different pieces and different moves that they each make. particularly troublesome was the knight. they are really bright kids (top in their class and my 7 year old already skipped a grade) and i think that teaching them to love chess will really benefit them both greatly. if any of you grandmasters have any advice on how i can better teach them the basics id greatly appreciate it.